Hi priestlake,
It's probably not broken, did just one end come off the rail and leave the rollers in the track? If so, fish the roller out of the pocket with clothes hanger or something like that. On bottom of roller hanging down is usually a white plastic lever and hook thing. Align roller with place on top of door where it hooks up and reinsert into door. You will need to open or turn the plastic thingy to let it go into slot or fitting on the door, after it is in place turn plastic thingy to lock.
This is usually what happens and it is usually the inner one that does it. Some times you may need to remove the wooden fascia trim to get access to the roller and top of door.
Let us know what happens..
Jim M