There's no back information on what actually caused your rock to become dead rock.
What was your detectable ammonia at it's peak?
I'll tell you my experience, and you can then figure out what you want to do.. So far my experience is working out. We'll see though. I did a limewater OD on my 55g reef. Ammonia peaked at 8.0ppm. killed everything, rock, corals, and I rescued the fish (and it lived to this day.)
My rock was dead rock. I did a 50% water change. I filled a 30 gallon tub with fresh RODI saltwater. Threw in a heater and a power head.
I filled 2 5 gallon buckets of the waste water from the water change. I purchased $4.00 scrubbing brushes (plastic). I took one piece of rock at a time in one bucket of saltwater and scrubbed and scrubed it. Swished it etc. Moved it to the next bucket of water change water and swished it somemore then let it rest in there while I did another rock.
Once the "cleaner" bucket of waste water was full of rock, I took them out and moved them to my 30 gallon tub of heated fresh salt water.
I did this with about 60- 70% of my rock. The first bucket where I scrubbed the rock off in. had about 2 - 3" (maybe more) layer of black sediment. The water was pure black after scrubbing just a few rocks.. The next bucket after doing half the rock, was starting to turn colors too. It was gross and horrible.
In the tub of fresh water, the ammonia the next day spiked out at 2.0 (down from 8.0).
I left the 55g and tub run fish free and life free for 4.5 weeks. At which time, the tub came down to 0 ammonia (the tub had .25 until the 4th week, tank was down to zero by the 3rd week. I attribute this to the tank having some sand and a sump with some sand for bacteria to colonize in. The tub just had rock..)
At the 4.5 week point or so, I had to house a bunch of corals in my 55g, as I purchased a 125 RR tank.
I left the corals in that tank for two weeks while I recycled the rock that was in the 30 gallon tub in the 125 for two weeks. I threw in 3 cubes of mysis, I got nitrites detected at .1 to .2. No ammonia was ever detected and 24 hours later the nitrites were at 0 and nitrates remained at zero. The rock was very cycled so, I think it was fine. I had corals even ressurrecting themselves on the old rock.
Just yesterday, 6 weeks after the 8.0ppm ammonia. I moved all the corals from the 55 to the 125g. As of this morning, all corals are doing great and not a single loss other than a head or two of candy canes. Not unexpected, but the rest of the heads are doing fine.
I have 2 fish in a QT tank that after I test nitrites and ammonia today and tomorrow assuming everything is o.k., I will be moving over today or tomorrow.
If your rock and tank are dried out. Depends on what you want to do with the rock. You can clean it, give it some type of acid bath to cleanse it of phosphates and debree and any possible heavy metals.
Whatever you do, it's going to be starting all over. I didn't do any thing but scrub my rock in salt water. Since your rock is dry, I would scrub the crap out of the rock and then start over with a full cycle. I don't think you have to buy new rock.
Just fill the tank, scrub down the rock in any water. (Fresh RODI would probably be fine) and place the rock. Thrown a couple good size pieces of shrimp in a filter sock, and wait a week or two until you detect ammonia. Pull the sock out, and wait another 3 weeks.
Then you should be good to go.
