There have been prior posts on intermittent failures of speedo and other cluster indicators. A poor connection somewhere in dash the probable cause, but difficult to troubleshoot.
Assuming no recent work in the dash area that could be rechecked, a gentle tap on dash with fist is recommended to restore operation if it doesn't self-restore.
I experienced a similar problem for a few minutes, a couple of times, 2 years ago, it simply went away.
