23 year old son has completely disengaged

I agree with the ADHD suggestions. Not coping at uni was when my friends child was diagnosed. But you will have to wait until he will engage with you first.

Many years ago, I worked in an inner-city residential drug detox unit. We had a core of regular "revolving-door" clientele. Cannabis, heroin, amphetamine, and also alcohol. If they managed to stay the month-long medically supervised detox programme, they could progress to a longer, six month residential treatment programme.
Both these programmes required the service users to be committed to the detoxification programme. They could (and did) leave at any time, knowing that, if we had a bed space at the time, they could ask to come back. About a third of them overdosed and died. Another third managed to reduce their use sufficiently to be able to function reasonably well in the world. The remaining third, often after years of "revolving door" dependency managed to get clean and stay clean.
In my opinion, the ones who did this were either people who glimpsed the possibility of a better life without drugs and kept trying after a string of failures, or people who found something that they desperately wanted and knew that drug use was preventing them ever being able to achieve it.
Without sufficient and consistent personal motivation, plus professional, non-judgemental support, it is extremely difficult to become drug-free.

How is the OP going to get him an ADHD assessment if he won't even see her? If he's lost his job and needs money can you help him out with ad hoc work where you also spend time with him? Yes you are basically paying for his attention but you need to find out what's going on. Getting someone with MH or addition problems that isn't engaging with family let alone admits they have a problem, is very very hard.

We have had similar issues in our family and extended family. Not as bad, but in both cases undiagnosed ADHD and in one case depression. Lots of signs to me that it could be that. Specifically the mess, the failure to follow through and taking drugs/drink to escape his mind. If he says he’s worried about you thinking he can’t cope - it means that he probably feels that he can’t cope.

Tough love stance would be the worst thing you could do. He needs to know that you are there, whatever. To help him navigate life and find his own way. Tell him that you empathise, that you understand, that there is no shame in finding some of these things tough - and that if he does have ADHD and/or depression, that life will get much much easier, with support. I doubt he is lazy - he’s probably been peddling very hard.

I had undiagnosed ADHD and made it through uni, first few years living in London and held it together - just. My room was a disaster, my self esteem was awful and I smoked and drank too much, plus went through a stage of being quite promiscuous. I totally cringe in retrospect. At age of 23 I read an article in The Times and couldn’t go to work the next day as kept thinking about how it was me and my life. Promptly diagnosed and learnt so much to help make my life more organised, calmer and really how to look after myself. It was transforming for my happiness. A big trigger for young people is leaving home and loosing that healthy support environment. The gentle nudges that help keep you on course. I think one of my biggest things was moving away from home cooking. Until my diagnosis, I lived off ready meals - extremely bad for nutrition and probably mental health.

I really hope you can help him. Tell him it’s no problem that you can’t tackle together. He will bring very hard on himself, which may make him prickly.

Firstly I would not be writing a letter.
It sounds like he may have moved on to a harder drug, cocaine?

He should write it himself. Presumably he's capable.

Me too.

Im sorry OP, you must be very worried. But I wouldn't be writing an appeal letter for him, just leave him to do it himself.
I can understand he was frustrated - or more likely embarrassed - that you found out about the job from someone else, instead of him telling you himself. But that also may seem to him that you are keeping tabs on him.

Just tell him you are there for him if he needs to talk but he needs to sort this out himself, your daughter is right you have done enough for him, he won't thank you for stepping in, he will just resent you.

Meant to say, it could not be cannabis addiction, but a professional with experience in the area will be able to tell you that. I agree with PPs that it would be a good idea to consider ADHD etc as well.

This sounds like a cannabis problem OP. I know of people it has affected like this.

The priority has to be working out what is happening with his health. Finding out how much he is smoking would be a start. Are you in touch with his exGF or flatmate at all? They might be more forthcoming than your son about this. I would speak to a health professional too, they should be able to point you in the right direction.

Next is the mortgage, and trying to understand if it is being paid and if so how it is being paid. If he has a flatmate, is the rent the flatmate is paying enough to cover the rent? Once you know how much he is smoking, you can work out roughly how much it is costing him.

I think the job is a bit of a red herring as it doesn't sound like it's that suitable for him. Perhaps he would work better in a hybrid/WFH role. If he doesn't really want the job, is there any point in appealing it?

Once your son has the help and support he needs, ideally from a professional who has experience dealing with cannabis addiction, I think everything else will fall into place.

Wishing you the best of luck OP. You obviously love and care for your son deeply and I hope this situation resolves quickly and smoothly for all of you.

He is avoiding contact with you because he is ashamed. As he should be.

I was going to say this - he should be looking at getting an ADHD assessment.

My son was similar to yours in his late teens, early twenties. Like you I was very anxious but a friend reassured me he would change in his mid twenties and he did. I just Googled male brain development and found this.

At what age do male brains fully develop?
approximately 25 years of age
In fact, there are characteristic developmental changes that almost all adolescents experience during their transition from childhood to adulthood. It is well established that the brain undergoes a “rewiring” process that is not complete until approximately 25 years of age.

Could be a million things that's making him distant. If he's depressed then he needs help and you will have to force it on him, whether that means waiting at his flat till he appears or opens the door. If it's drugs or drinks then the same applies. You can't leave it. I will add though then when I don't like people, and that includes family, I distance myself. Not sure about what kind of relationship you've had in the past, I know you have said he didn't want for much and your marriage is fine but that hasn't got anything to do with the love he recieved or the care he had. I didnt want for anything but my dad showed me no love. Obviously I don't know the full picture but he just might not want anything to do with you for his own reasons.

https://www.youngminds.org.uk/young-person/coping-with-life/drugs-and-alcohol/

^^ they also have good resources about how to talk to a young person about mh issues.

Offer to be a sympathetic ear but stop picking up the pieces each time he fucks up. If he wants to appeal his dismissal let him do it.

I’m so sorry op. You must be worried sick.

How was his attendance at school and university?

This is the crux of the matter isn’t it?
He lacks commitment to things but why? And I imagine the pandemic didn’t help.

It could just be his youth and general apathy , and he was in the past depending on you to bale him out, but now he’s too embarrassed. Or he could have a mh condition or pd that’s only emerging now, or be nd, or by the sound of it, it’s the weed.

In your shoes I think I would need to try and find out which it is and try and get him some help.

I think at this point I would try and intervene. Even if it only stops him progressing to harder drugs although he may already be on that path. Weed can make you paranoid which is why he may be distancing himself from you. It can also trigger or exacerbate certain mh conditions.

He needs evaluating by a licensed psychologist and if he is smoking weed heavily or taking drugs he needs to go to rehab.

Getting him to cooperate is a major hurdle though. Keep going back to his flat. Keep texting. Tell him you love him so much and that you are worried about him. That’s all apart from offering to pay for a psychologist maybe?

Certainly do not write him an appeal
letter, although it’s good he still wants to work. He has to stop being avoidant and start facing consequences now. Hopefully you can help him to help himself.

This is very upsetting but the one good sign is he texted you and asked you to help appeal get his job back

No he didn’t - he basically told OP to fuck off but write him a letter!

You sound kind and supportive but he sounds cosseted.

Offers of cleaning, writing letters etc is just enabling him.

I would disengage right back but with an avenue back for him.

’No problem X - we’ll leave you to it. You are an adult as you say but I’m not writing you letters or enabling your behaviour. I’m here when you’re ready but I won’t bother you again.’

And leave it there.

Have a look at the symptoms for inattentive ADHD. It's possible your son may have it.

This is very upsetting but the one good sign is he texted you and asked you to help appeal get his job back

it seems he may struggle with work hours so maybe a job doing shifts or hybrid may suit him better

he obviously feels terrible and sounds like he knows you are disappointed
im not sure what your original text said

Im thinking he needs support and a baby steps approach - maybe seeing what support he wants with his previous job or finding a new one that will suit him better

maybe a completely non confrontational letter offering practical support and that we all have struggles and occasional job upsets
no judgement let’s see what we can do together and you are not going to give him a telling off

might need to leave it a day or too
obviously you can’t write a letter of appeal for him but u can help
I don’t want to diagnose any issue but some adults need a light non judgmental support for longer than others -

But presumably you only have his word for that. If he wants his job back, he needs to write his own letter.

I don't have any advice other than what's already been said by others, but I wanted to say you sound like such a loving and caring parent. It is refreshing to read about someone who is being so supportive to their child and acknowledges they're still their child no matter what age they may be.
I hope your son opens up for you, you sound like such a sweet family really.