Could have been a little debris right between the rim of the housing and the touch screen. This has been reported a couple of times.
If debris gets under the rim and slightly presses the screen, the reader seems to interprete this as a "touch" and blocks all other input. In this case, a toothpick (or anything not damaging the screen) is a good tool. I try to clean my display always from the rim to the center to make sure I'm not moving any dust and crumbs (I sometimes eat while reading) under the rim.
If your reader now works again, the little crumb or whatever it was probably has gotten lose!?
Anyways, glad for you that it works again.