I reloaded the OS from BlackBerry Desktop, and it seems to be working now. This feature isn't documented in the BlackBerry Desktop User Guide
, which is strange.
I'm glad that my PlayBook is working again, but I still don't know what caused the Andoid apps to stop working. I'm going to install each app individually, instead of doing another restore from BlackBerry Desktop, in case Desktop was the culprit.
There is a line that appears at the bottom of most Android apps which includes a back button (click thumbnail). I'm guessing this is what you meant by "back swipes"?