I can relate. My self esteem is awful.

Just when you start to claw some of it back, something else comes along that knocks it down. With me, it seems to stem from my constant comparsions to others. If I see something that is, in my opinion, superior to what I've achieved, then I instantly begin thinking that what I have is worthless.
I completely agree with Gus1234U however, praise for doing something right can feel wonderful no matter how small. I think praise is hard to get these days for some reason, at least, that's my personal experience. Maybe it's because the world has gotten so competitive - and the fact that those who work hard and don't draw as much attention as those who don't and tend to get forgotten about. That's always bothered me.
I've heard that hypnosis can be really effective. I think that rather than trying to give you fake self esteem they focus on changing your mindset and the way you relate to yourself. Sometimes all you need is a push in the right direction. The mind is a difficult thing to win against, after all. To me, the biggest battle has always been with myself and I'm still fighting. I wish you the best of luck.