When tile flooring feels damp, and no liquid has been spilt on it, it's likely condensation that has formed on the tile surface. This often happens with porcelain and ceramic tiles. If the tile surface is cooler than the warm, humid room air, the moisture inside the air becomes the dampness on the floor tile when the warm air and cool floor meet. The cause can also be standing water underneath the house. This moisture causes condensation on the tile floor above it.
Place a dehumidifier inside the room that has the damp floor tile. The dehumidifier draws moisture out of the room air.
Crawl into the house's crawl space to provide you a view of the ground area directly underneath the damp floor tile. Look for moisture, such as standing water.
Spread out a roll of plastic sheeting that is large enough to cover the ground moisture. The plastic acts as a moisture barrier, preventing condensation on the floor above, until the ground completely dries.