Can I get full custody back after cps gave my mother and I joint custody

It depends on the circumstances of why CPS acted. It depends on where you live. You need to give is more details if you want our help.

Well I live in Texas and in 2008 I had a child that was beating to death by a guy I was with at the time. So cps got involed well they had me go to canceling and pareting classes all of that and at the end of the case after I finish everything they gave my mother and me joint custody of my other son but mase my mom sole decission maker of where me baby lives. So can I ever get full custody back

Ever? Ever is a long time. You need to discuss this with your caseworker. If there is anything you can do, your caseworker will tell you what you have to do.

But this is pretty serious. I doubt if you can regain custody anytime soon.

But they closed the case in oct. 2009 I'm no longer having to deal with them

If you want to change the custody order you have to deal with them.