1993 jeep grand cherakee won't start. Good battery. Headlights work also interior lights work.

Have you checked the starter?

Don't assume the battery is good. It's best to remove it and have it charged and tested, which most auto parts stores will do for free.

Both ends of both battery cables need to be clean and tight.
A voltage drop test at the starter and/or starter relay may be revealing. Inspect all connections for looseness and corrosion.