Damaged garage floor tiles can, in most cases, be repaired. Even if the concrete floor on which the tile is installed is slightly damaged, the floor and the tile can usually be repaired.
Repairing the Tile
Remove damaged tile with a chisel and hammer, taking care to avoid damaging good tile. Remove any hardened tile adhesive remaining on the garage floor. Clean the concrete, then apply the adhesive and lay your new tile.
Repairing Damaged Concrete
To repair damaged concrete beneath your damaged tile, first remove any damaged tile. Remove debris from the damaged concrete and patch the hole in the concrete. Allow the patch to dry, then, install your tile over the patched concrete.