surveyor plan view only

Having worked for some weeks on a route in southern Belgium in the 1950s, Surveyor is now presenting me with just a plan view instead of the usual 3/4 view thus making it impossible to work with. Can anyone suggest why this is and how I can get back to the original view. Your help much appreciated otherwise I will have to ditch several weeks work and start again.

Have you tried to zoom in? It does go to map view if you zoom out to far.