There’s no reason to put up with sticking bypass closet doors, or doors that have uneven gaps against the jambs—especially since they’re so easy to fix. Usually the mounting bracket screws have loosened up, making the door sag and rub against the carpet or floor.
To fix it, you’ll have to work from inside the closet, so get a flashlight and screwdrivers. Start by pushing one door closed against the jamb. Hold it against the jamb while you adjust the brackets as shown. Do the same on the other door. If the screw holes are stripped, just move the bracket over a few inches and remount it.