I had a really difficult time too when I went, but I chose to go 1500 miles away, so there was no turning around on a moment's notice. Keep in touch with friends and family. Since it's a big university, try heading over to health services and hook yourself up with someone to talk to about all this. It's a HUGE adjustment, having some extra support will likely help. I am wicked shy also, but I had a roommate that was more outgoing and forced me to be more open. I started leaving my dorm door open when we were in there so others could stop by and say hello. It sounds like a big step, but you would be surprised to know how many people probably feel a lot like you do. Most everyone there has few to no friends at the moment. Even if you don't want to hang out, having a bit of other human contact can help. Can you go for a walk on campus? You will need to know where you are going for classes, so a walk would be a good way of familiarizing yourself with buildings and such AND you can do it alone
Give yourself some time to adjust to the new surroundings and way of life. If you still feel this lost in a few weeks, then talk about maybe returning home, but give yourself a chance to succeed. Take your kindle out into a common area, pick a corner if it feels better, and just try to sit there for 5 minutes. If you still feel freaked out after 5 minutes, return to your room (but try to leave the door open). While going away to school is a huge step, you can take baby steps in making it feel like a positive decision. I cried a lot the first few weeks of my first semester, but it eventually became easier. Going away to school was the best decision I ever made, but also the hardest. NWgirl is right, college is NOTHING like high school. See if you can psych yourself up for your classes, it might help take your mind off the social aspect of it all. ((hugs)) you can do this. baby steps.