How long does a refrigerator last unplugged? We are moving to a rental property. There is already a refrigerator there and our contract is 18 months so we want to make sure our refrigerator is worth keeping unplugged or if it will be better just to go ahead and sell the refrigerator so it can be put to use.

Why is my refrigerator making a sound like a cicada every few minutes? It keeps waking me up! And I checked, there is no cicada under my refrigerator. I rent, so I will have to tell my landlord on monday, that means i have to listen to this noise all night, all day tommorow, and all tommorow night, I am never going to get any sleep. Last time I had a problem with a refrigerator the landlord had the maintenance man switch it out with one of the refrigerators from an empty apatment. My cat thinks the noise is a bug and and it's really freaking her out.

Not sure about the noise, but if you are storing a refrigerator:
DO NOT CLOSE THE DOOR!

It will mold/mildew and be disgusting when you want to use it again. As long as you make sure the door stays open, it should be fine. The mechanical parts should last decades whether you use them or not (or at least, historically speaking they should, although the quality of parts may have gone down).

Noise:
Does your refrigerator have a water filter or automatic ice cube maker? Perhaps there is something wrong with the motor? Or it could be an electrical problem? Is it on a GFI breaker? I would try plugging it in to a GFI breaker if it is not on one already (to see if you have a fault) [edit: some motor/GFI combinations may trip even when there is no fault, so this is not a perfect test].