As many things around your house, some tiles may need to be changed at some point as they can develop obvious cracks.
First you have to check whether you stored tiles that were unused when you did your kitchen or bathroom.
If you can't find any, go to the tile store and look for a resembling model.
If you can't find a good replacement either, you can choose to buy a few pieces of contrasting tiles and randomly install them, replacing some good tiles too.
Since you're at the store, remember to buy adhesive also, the dealer will help you in choosing what you need.
Matching grout is on your shopping list too if you don't have leftovers at home.
Here are the other items you should prepare before starting the job: masking or painter's tape, grout saw or utility knife, glass-cutting tool, nail set and hammer, metal straight edge, cold chisel, putty knife, wood block, a clean cloth or sponge and safety goggles.
For starters, put masking tape on the surrounding tiles so that you protect them from scratching and chipping.
Spread newspaper on the floor to make it easier for you to clean the room when you are finished.
The old grout will be removed using the grout saw or the utility knife.
Use the straight edge as a cutting guidance and make an X mark on the broken tile with the glass-cutting tool, from corner to corner.
Next, place the nail set where the center of the X is and tap with the hammer so that the cracked tile is loosened.
Chip out the tile by using the cold chisel and the hammer.
After getting enough small pieces out, you can replace the chisel with a metal end putty knife.
Use an angle when tapping both, so that what you are doing is lifting the tile and not denting the drywall.
After removing the tile you should do the same with the old dried adhesive by scraping it with the putty knife.
If by mistake you make a gauge in the wall, you should fix that before continuing.
Be sure to clean off the dust before setting the tile.
Now you can spread adhesive on the back of the tile with the putty knife and put the tile in place.
Wipe away the tile adhesive, also called mastic, which comes out from beneath the tile.
Take the wood block, place it over the tile so that it protects it and hammer it until you obtain an even surface.
Tape the tile from side to side and up and down with masking tape so that the tile is held in place during the drying process.
It usually takes 24 hours for the mastic to dry.
Now you can grout the seams and apply sealer over the grout for its protection when it is dry.