Turn on a hair dryer and point it at the tile seam until it begins to heat. Pull back the seam once it is hot.
Vacuum the dirt from the exposed seam.
Apply masking tape to both sides of the seam area to protect the subfloor from adhesive.
Brush a flooring adhesive on the back of the tile. Push the tile back onto the floor and wipe off the excessive adhesive with a rag. Place a heavy book on top of the seam and leave it overnight.
Apply the seam sealer from the tube, following the instructions on the side of the package. Block off the repaired area until the sealer has had time to dry.