A plant can live and recover a long time...depending on the stress it is under. If its been dry it may be on its last legs, and if it just ran out of water very recently, it could recuperate.

Since it is in rockwool however, you have an added problem. If you want it to thrive, it will need more than just plain water in the long run, since rockwool has no nutrients in it, and is used in hydroponics where nutrients are added to the water.

SN