Jay,Remember everyone, once in a while goes through the phase through which you are passing presently. Nothing interests you,no one shows any interest in you . If you do not talk with anyone, no one cares to talk with you. No one shares your pains, defeats,wounds,misery.
Someone very correctly have said in another answer that if you can not tolerate your own company,how can you expect the others should enjoy your company?
So first of all try to enjoy being with yourself .Think and retrospect , What mistakes, errors you committed in the past that made you sad and make a resolution with yourself that you never will commit such silly,stupid mistakes again .
And enjoy your company means not taking to drinking or starting smoking or trying to seduce any woman/girl. Do it in a positive way! Try to learn good things. The one advertisement which i always remember goes like this'What was the last time you did something for the first time!'(it was an advt of major infotainment TV channel) Our life is so cyclic, predictable, routine that we do not even try to have vision beyond iminant immediate future.Rather if you will do or try to learn to do the things you know you will enjoy, it will reduce your pains and misery . I am 46 now and i too was going through a phase like you are when i was of your age . No one to talk to and was living in a bachlor pad. Just today while i was going through my stuff i found a diary in which i used to write something daily in those days. What is not there ?
Apart from day to day happenings datewise there are good quotes which i came across, then there were some paragraphs from the books i have read and poems and songs among other things.(Now its fun to find the rates of the things, like a minimum fare of a local train in Mumbai in those good old days)
and my own poems, planning and expectations from future , have written about the persons who are almost forgotten now and hardly i can recall some of them vaguely . The persons whom we think are ours are felt so remote and aloof that its hard to believe that once they were inseperable from us! This is only one example. On these lines you can do things like reading, excercising, writing. Even reading any newspaper completely would keep you occupied for good part of time . Learn to enjoy life the way it is and as it comes to you. Try to make your future but while making it never forget to enjoy the present.
Thanks for reading this rather long answer .