Bacteria and air

Is it still wet? I'm pretty sure that they won't survive since they need flowing water and fresh O2 to live. Couldn't you have left it in the tank? You should have put it in a pantyhose and rested it on top of the existing gravel. That way it would get fresh water and O2 and you could take it out easily. No matter just put that gravel back and get some fresh gravel from what was left in the tank.

as long as it stays completely wet, it will be good. if its in a sealed bag, toss some aquarium water in it.

Not only does it need to remain wet and have O2, but it also needs food- ie ammonia.

I'm sure there was probably some left over debris in with though.

As long as the gravel is MOIST it will be fine. The bacteria should be fine without food for a day. Our beneficial bacteria is much tougher than most people think. I've instantly cycled several tanks using established sponges that were in a ziplock with a splash of tank water overnight.

just keep it wet and supply it with some food- throw in pinch of fish flakes and you should be set.