Step 1: Redrive popped nails. If nails are sticking out far enough to get claw of hammer around them, pull them out first. To redrive them, hold nail set over nail head and hammer nail as far as you can into stud. Nail head will punch through drywall's outside layer of paper and into drywall itself. You can generally do the same thing with drywall screws. If the head has separated from the shaft (evident if the head spins without resistance when you put a screwdriver to it), you can also dig the head out carefully and remove it entirely.