I have been through stages like this so I send my love to OP and all of you who feel like this.
Go to the doctor and ask to have bloods done, there are lots of physical reasons that make you feel like this. While you are awaiting results get a good multivitamin and some liquid iron, a Vitamin D spray
Don't try to change everything at once. I think the hair cut is a priority, it will give you a lift
If it is an any way possible go outside every day. I am sure you aren't a hermit! I mean go outside purposefully every day.
Your purpose isn't to run or walk (though that would be good,) the point to to find some trees and grass, and enjoy seeing them and being near them.
I am really fortunate in that I live in a truly lovely place, mountains and rivers etc. It is being fully aware of the joy they bring me that has got me through some terrible times. When I lived in a large town it was the parks and green spaces that served the same purpose. There is something restful and eternal that demands nothing from you but your presence.
Find some meditation on YouTube, it can be a help in relaxation.
Listen to books on Audible or the like, you can use audio systems provided by libraries too.There are some interesting people out there.
Take up a craft if you are bored in the evenings, I crochet and it's a very mindful process, though I also watch TV. Or listen to a book.
If you have a garden, grow something! Food, salad in a container or some potatoes or Flowers, this is just the time of year to sow seeds or use plants to brighten your space. Gardening has been a lifesaver for me.
Ask friends to join you sometimes, it always pushes me to tidy up and make myself a little more presentable.
I am aware that I sound pretentious 😉 but I honestly have been in your shoes and I feel for you. I hope you feel better soon.