Well I don't thing it's a problem that you are no longer into partying. Maybe don't seek persons, you would like to interact with, find activities you like to do and then you'll probably meet like-minded people doing so. Dig into why you don't like to talk to your friends - do they have different topics - which you don't find important. Or maybe do you think they wouldn't understand what drives you or what is important for you. If so - maybe getting out of your usual waters and meeting new people (maybe of different age) could give you new interest in interacting with people.
If your loneliness gets somewhat depressing, try exercising like running, walks in nature or else. Especially getting out in nature (like woods or so) usually give me a better perspective about a lot of stuff. I also get a very physiological Down every December/January based on the missing sunlight, knowing that this is a natural thing helped me somewhat dealing with it. So if you see any regularities maybe check your body basics: Sleep, Nutrition, Sunlight, Sport - which can effect your mental state as well.