Ceramic tiles may crack or chip if they were improperly installed, have poor adhesive bonds or if a heavy object falls on them. Never glue a chipped tile back in place. Not only will it look sloppy, it also won't last. If you have a minor crack, you might be able to mask it with paint in a matching color. Mix the paint with tile filler, dab it on and then wipe it with a damp cloth after it's dried for a few seconds. If the damage is more severe, you'll have to replace the broken tile. If you're not confident in your do-it-yourself abilities, you might want to call in a professional. If you do want to take on the project yourself, there are a few steps to follow.
To start, cut around the damaged tile with a grout saw. Wearing protective goggles, wrap a hammer in a rag to absorb the blows as you gently break up the tile a little at a time. Be careful not to break the surrounding tiles! Clear out the old glue with a putty knife, being sure not to scratch or gouge the drywall underneath. Use a notched trowel to apply adhesive to the back of your new tile. Set the tile in place and put something heavy on it to weigh it down until it dries.
If you find that the new tile won't stick, you may need to sand down the edges and/or buy special glue made of the same material as the tile. Once the adhesive has dried, you should place grout around the edges of the new tile. When the grout dries you can wipe the tiles clean with a damp sponge or cloth.