Use a heat gun to loosen any adhesives. Tile that has been sitting under carpeting or other flooring will probably have some adhesive, but the heat gun will warm it up and soften it.
Work in two-by-two-foot sections to make sure the glue doesn't harden again before you can get to it. Loosen the glue with the heat gun and pry it up with a plastic putty knife.
Run your hand across the section's surface to make sure you've gotten all the glue off the tile. If the adhesive was thickly applied, you may have to go over some sections more than once to get it all.
Mix oxygen bleach powder with water as per the manufacturer's directions. Let the powder dissolve thoroughly in the water.
Pour the mixture onto your ceramic floor, letting it get into the grout lines and soak. Leave it on for 10 to 30 minutes.
Use a hand scrub brush to get into the grout. You shouldn't have to scrub too hard, but you want to get as many stains out as you can. Pour more of the cleaning mix onto any stains and into the grout as you go.
Mop up the cleaning mixture with a dry sponge or towel and rinse your floor with clean water.
Repair Tiles and Grout
Repair small chips in your tiles by painting them with ceramic tile paint. Most ceramic tile paint is a mixture of oil paint and epoxy, so it will fill in the chips as it matches the color to the rest of the floor.
Fill in deeper chips, cracks or missing corners with epoxy putty and let it harden. Sand the putty, then use the ceramic tile paint to match its color to the other tiles. If the grout around a missing corner is damaged, remember to leave room for the grout later.
Remove damaged grout with a grout saw, which you can get at most hardware stores. Apply new grout to the areas that need it and let it dry.