What is the danger about revesing a gasto by pass I have has trouble since I have had the gasto by pass and the doctors was saying the only thing to do is reverse it back which I was told it could not be revesed.

You should be talking to a good doctor, getting a second opinion if you have to, not asking online.
Many people have difficulty at first, but we don't know how long it's been, or even what kind you had.
It's a VERY serious operation and not to be left untreated if there are problems.