It is possible you have minimized it down so far you cant tell what it is.
If the property sheet is undocked you can actually move it off of the Access Window.

See the screenshots below.

If you hover over the very right edge of the Access Window you should get a double headed resize arrow.
If you are right on the edge it will resize Access.  If you move very slowly to the left it will go away then come back again.  That would be the edge of the Property window.  Right Click and hold that one and move to the left to open up the Properties.

On the tool bar click the property sheet on and off while watching the right edge.  That should show you where the property sheet is if it is docked.
If it isn't docked you still should see it flash on and off.

There isn't a setting that I am aware of to be able to select the property sheet on or off other than the tool bar.

Are you by any chance using multiple monitors?  If so you might have drug it off screen.
See the Move Windows for additional ideas.