Sony Ericsson problem - screen reversed, now only readable in mirror.?

[DJW GT]

As the title says, somehow the screen of my Sony Ericsson Cyber Shot phone has managed to reverse, so that now the only way to read what is on the screen (without considerable effort) is to hold the screen up to a mirror so everything is flipped back to the way it should be. I have no idea how this has happened.

Any phone experts out there know why this is happening? All help and ideas apprechiated.

Thanks, Dan.