Camera shows gray screen Recently I was working on creating an animation in Cycles Render, and my camera started showing only gray when I switched from the Camera View (by toggling 0) to the User Perspective. Similarly, if I try to move orthographically within the Camera View it shows only gray; here the location numbers become enormous (again, not sure why) but this doesn't occur in the User Perspective and it remains gray.  I tried to find a solution to this on the site, but the common problem and solution seems to be with clipping distance, and mine seems to be large enough. I think I toggled something by accident, but I can't determine what. The screenshots are of the different views. 
Sorry if this question is simple, or redundant but I tried to figure it out and am at my wit's end!
From your snapshots it looks like your camera shifted a very long distance, try to adjust the camera location or the camera clipping.