sliding doors go south when two things happen, dirt and grime in the tracks and one of the adjustment rollers gets caddywompus.
What you need to do is to: get a level and a phillips or reg drive and make wheel adjustments as to achieve door level or to make each roller carry the same weight of the door and BE PERFECTLY PARRALLEL TO THE TRACK.
In most cases the door does not have to be removed, but in your case you might need assistance.
If the door does not close properly on the leading edge, I would assume that the roller is too low and needs to be raised so the nose does not drag or bump on the track. If the door does not retract, opposite from close, then the front wheel is too high causing the opposite leading edge to drag and bump the track.
First set a small level on the door horizontally and see if the door is level, but of course the floor might not be either. But the track, door, and floor must be together regardless if one is off level or not.
When its all adjusted, then periodically spray wd40 or some graphite dust on the workings to achieve a nice and smooth ride. Graphite might be too messy for the carpet in that area unless you are careful and liberal.
Last but not least, sometimes I have been at a home with the same problem and its not any of the above, its a screw head that was not counter sunk or driven down enough and the door track was hitting the screw head. Check this out also, its an easy fix.