Hi Farah,
If the orchid roots got too dry, they may not be able to take in water, and adding more will likely (as you guesses) rot them. It is probably time to unpot them and place them in a partially sealed zip lock bag on some damp sphagnum in a more shaded area. If you post a photo it will be a bit easier to help you. I'm guessing you have a phal orchid.
Cheers,
BD