How to acquire self esteem and exit from this vicious cycle?

I’ve spent these last months in numbness. Just the usual routine: gym, home, work. I’m 20 and i’m constantly told i should live my life. I see couples everywhere, people on dates, people texting. Nobody ever texts me, i’ve never had any kind of experience with girls… i simply have 2 girl friends and that’s it.

The idea of a girl liking me back seems a dream-like situation. I’m currently trying to forget about a girl friend i really like and everything seems impossible to me.