keys stopped playing, buttons stopped working...

I was trying to play back an animation to see how it looked after making some changes in the graph editor. Upon entering the 3d view I could no longer rotate or move my camera and several of my keyframes just weren’t playing with the animation, as if they weren’t even there.

Dunno if anyone else has had an issue like this or knows how top fix it, but I’ve already tried restarting Blender and that didn’t do anything.

Please attach a .blend file so we can pinpoint your problem.