Sliding doors should glide open and closed, not grind along like a Jawa sandcrawler traversing the deserts of Tatooine, or worse—refuse to open at all. There are plenty of how-tos across the internet that immediately launch into “remove the door,” but this isn’t one of them. Your door will stay in place while you troubleshoot.
Check the door
I have not studied the design of every slider installed across the world, but it’s fair to say that most of them run on tracks. My sliding glass door, for example, straddles a single metal rib. If your door won’t move, it may have jumped off its rails. In that case, see if you can lift it back on yourself or get someone to help you.
To do so, push the door open far enough that both sides are grabbable, then pick the door straight up. You should be able to maneuver it back where it belongs.
Clean the track
Because sliding door tracks are on the floor, they often fill with dirt and other debris tracked in by people and animals passing through the doorway.
Use a small brush, like an old toothbrush, to dislodge as much grime as you can, then vacuum it all up. First deal with the portion of track the door isn’t on, then see if you can push the slider over and clear out whatever was under the door itself. Moving the door may have dropped some crud on your clean track, so repeat this process as necessary. When you’re done, you can spray the track with WD-40 or a silicone lubricant, which won’t attract dirt.
Adjust the wheel height
Look at the bottom of your slider and see if there are holes or circular plugs. Most sliding doors have adjustment screws that raise and lower the wheels that carry them, and access is often covered by a round piece of rubber or plastic for aesthetic reasons. Mine are at the bottoms of the long sides of the door, with no covering hiding Phillips-head screws.
[Related: How to repair window screens]
If yours are in stealth mode, carefully pop that plug off with your fingers, a knife, or some other tool. Then use a screwdriver to turn the screw clockwise to lift the door up and counterclockwise to bring it down. See what works best for your door.
Take a closer look at the track
If your door still feels balky, the track might be damaged. Get down and inspect the length of it, searching for any dents and other malformations. You really don’t want to replace the entire thing, so gently try to work out any kinks yourself. Many bends can be straightened with hefty pliers, and you can grind down jagged burrs with a metal file.
Resign yourself to removing the door
If these tips don’t work, you’re probably going to have to take the slider off its frame or hire someone to do so. If you want to attempt it yourself, there are plenty of sliding door repair guides out there, but I think this step-by-step from This Old House is one of the best.