Our home had a wall with stuck on tiled 12 inch mirrors. In removing the mirrors almost all of the underlying drywall surfaces were torn to some degree. I have very little experience with drywall and wondered if those types of surface problems are repairable with compound or do I just need to go ahead and replace all the drywall.
Depending on the extent of the damage (how large an area) and what time you can invest, either way will work.
If the drywall damage is an area of more than 2-3 , 4 x 8 foot panels it would be less costly and faster to install new drywall (depending on how the wall is situated and it's location). If the wall has no natural transitions or "breaks" you will need to install panels so all of the wall is covered.
If the damage is not extensive than patching is a fairly straight-forward process. It involves cutting loose flaps of drywall paper off the wall face, filling deep gouges with joint compound, covering any broken or severely damaged drywall with joint tape (or replacing small pieces with drywall) and than sanding the dried patched sections and applying a second coat.
These can be fixed, I do it all the time, but it's a bit time consuming, but easier than replacing the drywall. To do this I first cut around the torn area with a sharp utility knife, cutting about 1/2' wider than the apparent damage. Then peel off the part from the cut line towards the center of the damage. Next, remove any loose peeling brown paper. Then apply a product called RX-35 sold at Home depot which is made specifically for damaged areas like this. If you apply drywall mud right over the brown paper, it will bubble, then you'll scrape that bubble off and coat it again, and it will bubble again, and again. With a coat or 2 of the RX-35, it wont. Or buy a can of Oil Base primer such as KILZ, and coat with that. It's not as effective, but it's better than nothing.
Then you can proceed to coat the areas with mud and texture them to match. I recommend getting them as smooth as you can, then skim coating the entire area, and sanding that smooth to ensure the best finish, since you'll likely have a ton of little repairs all over anyway.
This is NOT easy, as drywall repairs are an art, but with patience, practice and some skills, even a beginner can pull it off.