Drywall anchors are the secret to attaching loads to drywall without screwing into the studs. However, drywall anchors can have problems
If you’ve used drywall anchors to attach a shelf to a wall and the shelf has started to droop when loaded, there’s a problem that needs to be solved. It’s a combination of the anchors not being strong enough and too much weight on the shelf. In this instance, replacing the drywall anchors with something stronger, like a molly bolt, will usually solve the problem.
Where the drywall anchors won’t hold in the wall, the problem is usually in the drywall itself. If it’s become damp and is crumbling then it won’t retain the anchor. To solve it you’ll need to replace the area of drywall.
The problem could also be with the type of drywall anchor. If it’s pulling out of the wall very easily, the anchor is probably too small, or not the right size for the pilot hole. The anchor needs to fit tightly in the hole. Select a larger sized anchor. You should have to tap it in with a hammer for an ideal fit. Make sure the screw is the right size for the anchor.