Lopsided!

My son refused to eat on my left side so I just pumped that side and he ate from the right... Eventually it got to where I didn't pump as much and *skipping forward* now it looks deflated as ever! And if I pump it barely any milk comes out... Before that I put him on it about a month or so ago and it hurt so bad; Made it crack and bleed a little.. So nomore left boob! How can I get it back active to get milk? My right has no problem and I don't want it to go out too! I want to breast feed atleast until he is 1