Rear view camera fault

Screen pictures have suddenly reversed. e.g. So rear step now appears at top of screen rather than bottom. How can this be reset please?

You probably have a remote control for the camera.  One of the buttons will cycle through 4 picture positions
Mirror, , normal rear as if you were looking out of th eback window, mirror inverted, and normal rear inverted.
On my remote the button is marked "Mode Select" and it is the button nearest you as you point the remote at the screen.

Thank you Ron. My monitor only has touch screen controls - for  on-off, brightness and switching between the twin camera. I cannot find a manual for this model which may be a Vega? Somehow I must have Inverted the image via the touch controls,but don't know how I did it?

Sounds the same as my monotor. There are 4 touch senstive areas at th eright of the screen equally spaced down the right hand side.  As you say, one is on/off, another is AV1 or AV2, the third is brightness, contrast and the fourth is the mode whiich does the mirror, invert etc.  I see that the modern ones have 5 areas - from the top AV1/2, up, menu, down and on/off.  Th emirror settings will be somewhere in the menu.  You do have to be fairly quick navigating the menu! 
See http://www.ebay.co.uk/itm/like/201296062076?lpid=122&chn=ps&adgroupid=41285909471&rlsatarget=pla-278687452483&adtype=pla&poi=&googleloc=1006495&device=c&campaignid=738225731&crdt=0

Thank you Ron....will try to reset tomorrow. David