Stuck in a routine

I’m a 23 year old self conscious nerd. I’ve got no confidence and bottle up my feelings as I am unable to express them. My social life is non-existent and I spend most nights watching telly or playing computer games by myself. As a result, I have never had a girlfriend and never even been kissed. This has been my routine for some time now and don’t know any different. The problem is I am now feeling more and more lonely. It never really used to bother me much, but lately it is really getting to me and don’t know what to do about it. I haven’t got any friends and so find it difficult to go out anywhere to socialise. I have always been much more of a listener rather that a speaker and so fade into the background in most situations. Again, this is to do with confidence. How can someone with no confidence in themselves get away from a routine and get out more? Not only to build confidence in myself and have a social life, but to find a girlfriend.