I'm 28 now and just recently got through almost the exact situation you are describing (diploma came in the mail yesterday).

So yes, I started off at college in Computer Science, figured out after about a year and a half that while programming is awesome (as evidenced partly by the fact that I hang around on this web site), the CS major at my school was significantly more hardcore about it than what I had imagined, and there was no way I was going to get myself to finish it. On top of that, although for the first freshman semester I had managed to be pretty social, by year 1.5 I was didn't really have many friends anymore other than a few people in my dorm, who were more like acquaintances than anything else. What I did to get out of that mess was largely trial and error, but I'll tell you what I can and hopefully it will help.

First thing I did was switch out of Computer Science. If you find that you've lost passion for your major, and you're certain about it, you'll be better off finding something you are passionate about, or at least somewhat interested in. I switched to Creative Writing, but continued taking CS courses on the side as part of a plan to get CS as a minor, but I didn't end up following through with that part. Of course now, having received my Creative Writing diploma, I'm not actually as passionate about that as I originally thought I was.

So while finding something you're passionate about is important, the bigger part is the self-esteem/social issue. I know that a lot of people will tell you that being introverted is fine and okay, but if you're introverted and your self-esteem is low, then that puts you between a rock and a hard place. This was the hardest issue for me to crack, and it took me the next 4.5 years out of my 6 total years in college (the latter 2 mostly part time).

Eventually what I did is that I also went to the counseling dept at my university and I was fortunate enough that it actually was somewhat helpful. It sucks that yours seems to have let you down, so my suggestion would be to try to ask them for some kind of referral to an external counselor, hopefully within your health insurance plan if you have one. Having a real live person that you can talk to about this stuff on a semi-weekly basis can be invaluable. I moved on from my college counselor to someone at a local clinic, and I still go to see them even though I would consider myself now to be in a much better headspace.

The second thing related to this that I would recommend is to try to make new friends by trying out some different clubs. I was able to finally find a solid group of real life friends almost by accident, when a new roommate suggested I go to the tai chi class he was going to. I figured what the hell, but now the people I met at that class are among my closest friends. The important difference is that these aren't just 'entertainment friends' -- people you hang out with for fun or going out. If for whatever reason I end up back in a self-esteem pit, I have no doubt that they would come over to my house and figure out how to get me out of it. Ironically, the 'find friends by joining clubs' thing was one of the things my parents had been suggesting to me since year 1.5.

The last thing I want to say, and maybe the most important thing to impress on you, is that there is no 'quick fix' for this kind of situation. It took me 4.5 years almost to get from the realize-there-is-a-problem stage to where I am now. It doesn't have to take as long for you, but don't expect to get this completely turned around in 6 weeks, or even 6 months.

Good luck!