Stripped bolt

Whats the best way to remove a nut from a stripped bolt? The bolt has a slot for a screw driver on top and it has a nut threaded onto it. I am trying to install a new power window motor (not on my camaro thank god :D ) and it seems someone has done so once before and in the process they stripped the bolts that attach the motor to the regulator. Thanks :)

Worst case is that you have to cut or grind the bolt off and then replace with a new bolt. I don’t know maybe try vise grips on it?

vise grips work wonders, you might have to tighten the vise gripps down with another wrench. I'm having a hard time picturing what this looks like, if you can get to the nut then you can use a nut cracker-not the kind you eat, its a tool you tighten and it breaks the nut in half

Thanks...I actually ended up sawing it off to the nut and then drilling it out. What an pain in the ass that job was! Took me nearly 5 hours!