65 mustang rear side window fell down
Your roller on the crank mechanism is broken. Been there done that...you can get a kit from any of the Mustang parts houses to do the repair. It's a tough job if you've got big hands. Take the back seat out, remove the crank handle, then remove the side panel. You'll be able to see the rollers and all of the bolts holding the mechanism to the chassis.
2 - 65 'stangs, 79 F100 SuperCab, 03 Expedition
Henry Ford said, "If you find you need a tool, you have already paid for it."