Sliding doors can sometimes be a bit tricky to open and close due, to factors like dirt on the rollers damaged tracks or a misaligned locking mechanism. If you’re experiencing this problem here are some steps you can try based on research;

1. Clean the Track; A buildup of dirt and debris in the track can cause the door to stick or become difficult to slide. You can use soapy water and a brush to clean the track.

2. Replace Rollers; Damaged rollers may be causing difficulty in opening and closing the door. It’s worth inspecting them and replacing any that’re necessary.

3. Adjust the Rollers; Ensuring that the rollers are properly aligned and functioning is essential. You can turn the screws clockwise to raise the door or counterclockwise to lower it.

4. Lubricate the Track; After cleaning apply graphite or silicone lubricant on the track to make it smoother for sliding.

5. Inspect the Locking Mechanism; A misaligned or damaged locking mechanism could also contribute to difficulties, with your sliding door. Make sure it is properly aligned and functioning as intended.

By following these steps you should hopefully resolve any issues with your sliding door being hard to open or close.
To ensure that the sliding door remains easy to open and close its recommended to avoid using substances, like oil, lithium grease or spray lubricants that tend to dry out. By following this advice you can effectively address the issue. However if the problem persists despite your efforts it might be an idea to seek help, from a repair specialist.