my reverse does not work in my 2002 grand am se poniac..it worked that morning but when I went to reverse out of the drive way at 430 it would not work.. all the other gears work fine except reverse so idk whats wrong with it?

I'm going to have to say that a critical link to engage reverse, has fallen off, or is grossly mis-adjusted because what you need is a tranny mount and/or motor mount~

put a jack with woodblock to take it up from under the oilpan perhaps 3/4 of an inch to see the splitting and degradation of the rubber pieces~

this is the piece you are going to inspect~