Running latest version of El Capitan and Aperture.

Aperture seemed to to be working fine, then after doing some searching  through some pictures I am now unable to view any picture in main  viewer screen.

Press F key and I see pictures with black background as normal. If you double click on one picture you get taken back to browser - just grey back ground as normal but no picture. 

In split view no main picture, just the small previews below. Sometimes able to scroll through pictures at bottom of screen, sometimes this does not work. No search bar visible.

In browser view pictures are at top and are off to the right and not spread evenly on the screen as normal.

No search facility as normal showing.

Any ideas on how to rectify this?