I had a simular issue with the rear door on the xj, I don't know if the front door is the same, but you remove the few screws that hold it in, the screws that hold the trim around the handle if it has it, and pull the window crank if it has manual windows. then yank.
the problem with mine was that the latch mechanism was really gummed up with different lubricants that it would not move anymore. once I managed to get the door unlocked and opened I took the latch out and cleaned the crud out of it. I plan to use some graphite to help it too.
hope that may help.
good luck