The reason for this may be that the SD card inserted into Palette was bumped, or something may have occurred within the electronics of the screen.
However, there's good news – Palette is still working! The screen may not be displaying the most relevant information, but your Palette/Palette will continue to create filament like it normally should. The screen will return once your print is complete, and you are able to restart your Palette.
If you're finding that this is a constant issue with your screen, we suggest printing and installing screen washers to help reduce the amount of static. You can find the STLs for the washers here.