Most patio doors run on roller wheels that are fixed onto the bottom of the door frame - can't really comment on your installation but mostly these wheels are adjustable. Usually there is a hole near to these wheels that you can pass a screwdriver through, on the door end. If you can find the screw inside and turn it, the wheels will either rise or fall and allow the door to once more run on its track, as intended.
John
February 2008