Forget boiling and all that junk. Its not necessary. With no fish in the tank Ich can NOT survive. Within 24 hours it will be completely gone. 48 hours to be certain. If its been that short since the last fish died, ich is probably still present in the tank. I would go buy some cheap fish, but hardy fish... like giant danios or tiger barbs. Get something back in there right away or you're going to lose your BB in the filter and gonna have to re-cycle your filtration system again. Throw some fish in there and treat the tank with QuICK Cure made by AP Pro. Raise the temps to the high 80's and add some salt to the water. 1 tablespoon for every 5 gallons.
''Rid Ich'' and ''Ich-Attack'' I've never had any success with. Normally I would only treat with salt and temps. But in your case you just wanna kill the ich asap and get your tank running back to normal.
So just throw some hardy cheap fish in there, medicate, raise temps and salt the tank and after a week, do a 50% water change and add the fish you want. Ofcourse add them slowly.
Myself, I always have a 10 gallon running. After I buy a new fish, I place it in there and treat the tank w/ QuICK cure for 3 days, do a 50% water change, keep em in there for another 3 days and on the 7th day I take em out and toss em in the desired aquarium.