Have you lost the magnet from under the kickstand?

I stupidly coloured the inside of the camera slider in black to try to get rid of the blue hue, only to realise the camera uses the black/white blocks on the inside of the slider to register whether the lens cover is closed or open, I then spent the next 45 minutes wiping off the marker pen live and learn ay.

Maybe you've changed the distance between camera and lens cover and therefore the camera is not registering the lens cover being opened.

Might be worth taking the back cover off and pushing the lens cover from the inside out, see if you can click it back into position.

This is all a bit of a guess so don't flame me too much if it doesn't help.

You can get replacement back covers, I have the link somewhere and will update this post when I find it.

Didn't take as long as I thought it would, here you go:
http://www.thenokiaparts.com/eng/tuo...00-spare-parts