Fortunately it's easy to revive them. Irises spread by underground rhizomes, a storage organ similar to a bulb. Plants can be split apart and replanted in the autumn or spring. It should be done ...
Using a shovel or spade, carefully remove the iris from the ground. Try to lift the entire clump of rhizomes or bulbs (depending on the variety) from the ground at once. Shake or rinse off excess ...