How do I reinstall this?

To be honest, I don't think I need to purchase anything from you, but perhaps you will help anyway?
I have a closet that uses the 23-214 : Wardrobe Door Roller Assembly, 7/8 Dia. The door separated from the roller as shown in the photo and I cannot figure out how to reattach the door -- the screw rod seems too long to slip the door under it. Can you help?

Thanks, but my problem was actually how to get the roller out of the rail as it seemed trapped (there are ridges on the upper surface of the rail to prevent the top rollers from rotating out of the track. I found another source that pointed me to two slots cut out of the ridges, they were further along the track (past the mid-point) so I hadn't noticed it. 

Now my problem is that the screws have stripped out of the wood. There is not much composite material between the screw hole and the threaded tube collar (which the roller threaded rod screws into, the middle component in your photo, and the plastic sleeve that goes over it) and the wood has broken away on both sides of the tube. Much of the weight of the door (easily 50 lbs) is supported on those two screws - not a great design IMO (not your fault!).

Any suggestions for how I can beef up this part of the door so I can remount the assembly? Or is there an alternative roller assembly that would fit the door... like the middle component in the photo, but may be with longer wings (to go into new wood) or with two screws on each side to better support the weight of the door?Thanks.

Seems I have a problem similar to Colorado's: I need to remove a bi-fold door to repair/replace the base support piece which has been crushed by an appliance moved across it. My previous experience with bi-folds is to simply depress the top roller mechanism to pop the door out. This two-wheeled roller seems trapped in the track with no obvious way to release it. Is unscrewing the track really the only solution to free the door? Thank. Randy