I'm sorry that you are feeling lonely and depressed. I think that I had two real dates in college and no real boyfriend. It was a lonely time for me and for many of my friends. It's difficult when the world seems to revolve around couples and you're single.
Things improved immensely after college. Not only for me, but for many of my friends. The only advice that I have is to put yourself out there if you want to start dating. Tell your friends and family that you are looking to meet someone. They might know someone. If they don't, don't be too disappointed. People meet in strange ways. I know someone who met her fiance by going to her church and asking her priest to pray for her to bring someone special into her life. The priest said that he knew someone who is looking also and introduced them.
Many people meet at school, work, volunteer groups, church, and even bars. I wish you the best.