if u stoped 4 aa wile then i now what u mean its probly because u think that u will fall on ur head or somthin like that

Sometimes gymnasts over think the skill they are practicing. They tend to subconsciously think of what may go wrong so they freeze up. You may practicing on the trampoline for a while and once you get comfortable with that, move to a mat. If you're still a little scared to do it on a mat, ask your coach to spot you on the first one then just be there for the next one. Once you're fine on the mat, do the same thing on the floor. It's going to take some time to get comfortable with doing them consistently, butt I know you can do it. Good Luck!