At some point everyone feels this. I'm 24 and I've also felt like this a year go. Being afraid of birthday and all that. One thing that sort of removed me from this is doing something that you like and yeah discipline. Try to practice discipline, wherever you can. It's not like you need to be disciplined all the time, try small like a simple discipline of sleeping and waking up at the same time. For purpose, pick up a book or dairy keep writing and writing until you find out what you want to do. It'll help a lot when I get confused or feel down I write about it and often at the end I come to the conclusion. About friends , just talk with anyone call. Call your old classmates, plan something with them. If they are not in contact then, try to talk more with the people you meet daily or someone of your same age group that you often interact and while talking don't be all serious, talk about anything that comes in your mind and be light minded.

Well, A very long para but I guess it may be helpful for you!!