The type of drywall service you need depends on the condition of your drywall and the severity of its problems. Your two options are either repairing or installation. If something fell and created a small hole in your wall, you can easily find a local drywall contractor to repair your damaged drywall.
If your drywall is severely damaged, for example from water damage, it may be necessary to install new drywall panels. Severe water damage is apparent through visible bulging, crumbling, cracking, and collapsing.