Hi Mavis, welcome to the forums and sorry to hear about your loss

If the tank is left without fish, as Mearwynna mentioned it would die without a host. I think the time span varies depending on the part of the cycle the ich is in.
I have also heard ich cannot live out of water, so you could always try drying everything out - but do double check this, as I'm not 100% sure how true this is, or how long things need to be dried out for, having never tried it myself.
Mavis I also found this website that has some information about Ich that you may find useful
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And an article about treating ich with salt
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It will probably be a good idea to do a fishless cycle as others have suggested, unless your tank is already cycled?
Do you know what your water parameters are? I.e. Ammonia, Nitrite, Nitrate and PH levels?
Best of luck!