Can you give us some more specifics? How often do you water it? When was it last repotted? What soil mix? How close to the window, and what direction does it face? If the plant appears to be rotting, you can always take cuttings of stems or leaves, and start over. Below is a link that might be helpful.

Here is a link that might be useful: Jade plant tips

I think that improper watering of succulents is common. People are so concerned about overwatering that they either don't water often enough, or they give their plants little bitty sips when they do water. Both scenarios will cause the 'wrinkling' (which is a sign of wilting in jade and other succulents).

When it's time to water these plants, they should be drenched thoroughly....even allowed to sit in water for awhile. Then the drying cycle can begin again. If your potting medium is coarse and fast draining, you'll not have to worry about the soil remaining too damp for too long.

I'm not saying that this is the problem with your plant, but it's something for you to think about. Chronic overwatering can kill roots, which will also cause the 'wrinkling' (wilting). It's up to you to determine what the tarnation is going on. ;-)