24 hours... that's a tough call. Is the fridge relatively full or empty? In these scenarios, full is better. I would get an IR reading of various parts of the fridge as soon as the power comes back on. If it's 60 or below, that, to me, would signify that the cheese hasn't spent too many hours outside of fridge temps. North of 60... I wouldn't toss the cheese, but I'd use it quickly, and, if it smells the least bit funny, then I'd probably toss it.
That's totally a gut feeling, though, and I'm probably erring on the side of caution. Mozzarella predates refrigeration.
If you do save the cheese, you might want to toss it in the freezer for a couple minutes to quick chill it, making sure not to freeze it. The faster you can get it back to fridge temp, the better.