I have an umbilical hernia and I have always been able to see it and feel it but now I can't see it or feel it unless I cough is that normal?

Yes. That is very normal. The defect ("hole") doesn't disappear but the bulge (tissue coming through) may move in and out, making the hernia seem to change in size. Cough will exacerbate the bulging. The hernia should be fixed if you are healthy enough for surgery to avoid complications from it.
Umbilical hernia . Not seeing it is better .