Thanks, helps a great deal.
If the speedo is receiving power and seems to otherwise work, the issue most likely is with the Vehicle Speed Sensor located on the transmission just behind the top cover. They can quit working if metal fragments collect on it.
If you can get to it, remove the mounting screw and clean it off. Reinstall and you should be good to go. But if that doesn't work you'll need to replace it. That involves removal of the battery and tray and the seat as the electrical plug is hidden there.
But if the speedo shows no sign of working you'll need to check the fuses, grounding, battery, and the plug to the unit. There remains a remote chance the speedo unit itself has gone south, but that unlikely.
If you don't have a Service Manual, get one. Best investment you can make.