Black render all of a sudden.

Hi there.

For some reason, all of a sudden, all my renders produce a black screen. OpenGL produces images, but Cycles doesn’t. I can’t think of anything I’ve done that would cause this. The render settings are correct, the lighting in the scene is correct, I’ve been through everything I can think of including restart and reset. I was playing about with gravity on a couple of mesh objects, but they are now deleted. I was also playing with a repeating path, but those objects are also deleted.

Has anyone come across this before, have any ideas?

Thanks.

Solved. Somehow, and no idea where or when, I had selected the wrong scene in the layer options on the Scene tab. God knows how I’ve managed to do that!