If you've got a Melitta brand burr coffee grinder like model MEBG8B
but it won't grind anything, maybe you've got a stuck button. Here's how to fix it.
With our grinder, the buttons for 4,8,10,12 cups seemed to simply do nothing. It turns out that the shut-off button (top center) had jammed. Although I managed to get the button out of its cockeyed position, the grinder still didn't work.