Don't worry! It's really really normal. The poor wee thing is just a bit scared but he'll come round. If you have DC, leave him under there until you get them to school / up for a nap as he won't cope with them while he's feeling like this.
First thing to do is to stick a bowl of food and a bowl of water under there - being hungry will only make him even more scared. Then, when the house is quiet, lie on the floor near the sofa. Don't stick your arms under it, just lie where he can see you and if he's looking at you, make some very slow blinks at him - slower the better. That's the cat equivalent of a smile.
Be patient, and he will venture out. When he does, don't stroke him directly, but try holding your hand out in a fist, and he'll probably head-but it and then smell you. Let him get used to your smell again, then you can stroke him very gently.
If I were you, I'd then start the rehoming again from scratch. Put him in a small, quiet room with water, food and his litter tray and visit him in there being very calm and quiet when you do. It'll only take a few hours, IME, perhaps a few days at most before he's bouncing and brave and desperate to get out from that room to explore, and then you can let him learn about the house at his own pace.
If he's crying for his mum overnight, he probably needs something to sleep with. Ideally, he could sleep near you (I put a dining chair by my bed so I can do vague stroking in my sleep overnight) but if that won't work, get him a furry hot water bottle and make it slightly warm before you go to bed.
You should also want to consider a Feliway diffuser - not cheap to buy but they last for ages and are very effective. Most cat shelters / catteries / breeders use them for stressed or anxious cats. We foster cats and kittens and wouldn't dream of not using one for a kitten like this.