all of my gauges just stopped working and warning lights are on what may have caused this?
Maybe nothing more than a bad ground/ground wire.
where might this ground wire be located?
That is the tough part, It may be under the dash, or many other places. Often they can be found by looking, but a real shop manual will tell you where they are.
It is possible that if you tell use what year Grand Am you have someone here may be able to help. Also if there were different models for that year, let us know what model you have.it is a 1997 grand am gt