Though known for their durability, ceramic tiles can become damaged or cracked. Sometimes, they can even fall off the wall—a common occurrence in older homes, where settling can add pressure by shifting how walls align, potentially popping a tile off. For walls and ceramic tile still in good condition, simply reattach the tile. Complete a similar process when replacing a broken tile (with the added task of replacing the tile). A little work can make the tile look good again.
Remove excess grout from the tile. Try scraping with a utility knife first; old grout will sometimes crumble. Using a putty knife, remove as much of the thinset on the back of the tile as you can. Typically, thinset does not come off easily. Use a rotary tool with a grout remover bit or a diamond-coated sander bit to grind down the thinset and grout. Use a larger grinder with diamond pads if replacing several tiles in one area at the same time.
Clean the wall surface of thinset. Clean and level the wall and the tile as much as possible, which will allow for the new tile to properly align with the other wall tiles. Use the putty knife and rotary tool to grind down any difficult-to-remove thinset.
Using the utility knife, notch the cheap plastic putty knife with teeth every quarter inch—like cutting teeth on a pumpkin. The teeth will turn the plastic putty knife into a small thinset trowel that will allow you to work between the tiles.
Apply a coat of thinset to the wall and a light buttering to the back of the tile. Press the tile into the opening and work the tile until you've made it flat and even with the other tiles. (This step may require a couple tries to get the right amount of thinset for your tile wall.) Clean off any thinset on the sides or face of the tile immediately. Allow 24 hours for the thinset to harden.
Apply grout between the replaced tile and the other tiles using a grout float. Clean the excess grout off, then clean the tiles with a sponge. Keep the new grout at the same height and appearance as the existing grout.