I know what you mean, I've been in a similar mindset not too long ago. It's difficult to get back into being motivated but you just have to push yourself. You may not feel motivated to do anything or to socialise but the more you stay in that mindset, the worse it'll get. Even if you don't like it at first, push yourself to do more. Be more productive with your time and spend more time socialising with friends/family. Company will make you feel better and being productive will definitely help as it'll give you a sense of accomplishment.