To restore the softness to Play–Doh compound, try adding water one drop at a time and working it in to moisten the Play–Doh compound. You can also try wrapping the Play–Doh compound in a damp paper towel, returning it to the container and replacing the cover. Let it sit overnight.
Mix water into the Play–Doh. Seal the bag, then knead the water and the dough together. Start with just a few drops of water, to be safe, and keep adding water as you squeeze. Do not add so much water that the color bleeds and the bag becomes soggy.
You can easily prevent play dough from drying by taking a few preventative.. If the Play–Doh is so dry that it is cracked throughout, it may be too hard to revive .