my problem is
when playing space quest in full screen
i press windows button on the keyboard
this minimizes the game so i can use desktop
i cant seem to maximize the game back to full screen

Maybe it's common issue. Old games are sometime like this. Some of them crash to the desktop if you minimized it.

Try pressing
Alt + Enter
to bring the game back
to fullscreen

EDIT:
ninja'ed!!!1! :@

already answered in your previous topic no need to make doubles.

This is a standard DOSBox thing, not the game itself. I'm not sure whether it's a feature or a "feature," but alt-enter should fix it, regardless of which game you're playing.

Not only DOSBox; alt-enter is a semi-common keyboard shortcut for fullscreen that works across many different pieces of software. It should always be the first thing to try in these cases, closely followed by F11.

Ah, fun with misquotes...