Why My Rear Camera Wont Focus?

I turned on the phone and noticed that the rear camera of the phone no longer finds focus. It extends the lens, doesn't find focus and retracts back. So the lens itself moves, it just doesn't seem to find the distance to the object. I'm wondering if I should buy a spare camera to replace it or is there a fix for this. I was very gentle with the camera and didn't rip any cables or anything. Anyone have any ideas? Thanks in advance :)