- toggle the Print Preview tool button
- use File menu -> Print Preview
- close the Print Preview tab or sub window with its close button (right on the tab header or most right above the tool bar for sub windows)
Anyhow, before closing any modified drawing you should be asked if you want to save before closing.
Also there is usually Auto save which may have reduced hours to minutes. These files may be still there if you haven't changed the drawing meanwhile.
investing less than half an hour into Search function can save hours or days of waiting for a solution