Step one is to identify the source of the crack. If something was dropped on the tile, you’re good to replace it. But if it broke under normal use, there might be an issue with the subflooring that needs to be resolved first.
Contractors always recommend storing a few tiles from any reno for future repairs. If you didn’t, you’ll have to shop for a replacement. If you have a patterned tile it might be hard to find an exact match. Keep this in mind next time you update a kitchen or bathroom.
Use a grinder to remove the old grout and then try to pry the tile loose. If it doesn’t come up, you might have to smash it and remove it in pieces.
Once the old tile is out, you need to prepare the space for the new tile by removing as much of the old mortar as possible using a chisel or grinder. Once you’ve cleaned it up as much as you can, lay down new mortar with a notched trowel.
Lay the replacement tile in place. Plastic spacers make it easy to properly centre the tile. Just make sure that you use ones the same thickness as your existing grout lines.
Use a level to make sure that the tile is seated evenly. Unless you use quick-drying mortar, leave the tile to dry for 24 hours before applying the grout.
Buy grout that matches the colour that you have. Mix according to the directions, and then work it into place with a grout float, using a damp sponge to clean up residue. Stay off the tile for another day to allow it to fully set. After that, apply grout sealer.