Just opening or closing the door with too much force can warp the frame.
Sliding screen door stuck at top.
Most sliding patio doors have one or two small holes at the top and bottom of the door for adjusting the roller height.
Determine exactly where the door is sticking before deciding on a remedy.
Most sliding patio screen doors can be unstuck with a little maintenance.
If the edge of the door is hitting the frame try tightening the screws on the top middle or bottom hinge on both the door frame and the door being careful not to over tighten and strip the screws.
Again this is a fairly simple problem to fix.
These hole are often covered with a plastic plug.
If your sliding door is sticking or dragging along the tracks making a grinding noise the springs in the rollers could have become loose causing it to sag.
First look at the lower track.
Your door is old and worn out.
If the track is bent or squashed straighten it with smooth pliers and file.
If it fits too loosely in the tracks any vertical movement of the door will cause it to come unseated and it will fall.
Remove the plug and use a screwdriver to tighten and loosen the roller height making very small adjustments and testing each time.
Locate the spring assembly which is often on the top.
In some instances the sliding screen door will fall out repeatedly because it is too small.
Clean it with detergent and water or even a little solvent on a rag.
Find the rollers at the bottom of the door.