ah, don't sweat it dude. you're not a huge failure. you've already done much more than most people have attempted at your age and the real truth is that most companies go out of business. as long as you treated people fairly and behaved professionally then you should be proud of yourself.

what kind of work do you enjoy most? you've tried a few different roles now. focus in on the one that feels best. you have a CS background so maybe you want to get back into software development as a programmer.