Door Latch issues

I had some body work done on my Driver's side door about two years ago. SInce then I began having some issues with my door. The door seems to be sticking. It's hard to open the door from both the outside and inside. The other issue is the door latch sometimes get's "stuck" and will not allow the door to shut. When I try to shut the door it's like the door latch is still stuck in the shut position because it does not latch. I finally figured out a a temporary fix when this happens. I take a screwdriver and and push the upper part of the mechanisim until it pops up and then I can shut it. I know this is a temporary fix because when I pop the latch it feels really loose and I am now beginning to have to do this more often. Is there any fix that any of you know of besides replacing the entire door latch mechanisim? Also if this is the only fix. How difficult is it? Any insight on this helps. It's an annoying issue.... Thanks!