Assuming you know how to open the property sheet, it is probably minimized or hiding waaaayyyy off to one edge of your screen. Sometimes I move it way down at the bottom and forget. When I invoke to open it (on the ribbon) I actually close it. Not seeing it, I click to open it again - not there. Once I discovered it was hiding, I now know to look for it where I usually park it at the bottom. There might only be a sliver of the window frame visible, but it's there. It's normal Windows behaviour to place a window in the spot you left it in when you reopen some apps, so closing/opening Access won't fix it.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.