Just to clarify, your adjustments panel is missing? Or the adjustments you've applied to images are gone?
This may sound silly, but did you inadvertently hit the "I" key and toggled the inspector off? Or maybe the "P" key which would put you into Quick Preview mode? You can't make adjustments in Quick Preview mode and the panel grays out. Hitting either of these keys again will toggle these features on and off...
If it's something different, let us know.
