what is causing the speedometer not to work

no the speedometer is not working at all dash lights comes on

I did not ask about the SPEEDOMETER , we already established that it doesn't work. I asked about the ODOMETER (the vehicle mileage)..............

yes the odometer still works

Probably easiest & most economical to have the gauge cluster tested with a scanner. IF the odometer is registering miles traveled , then I would think the signal & sensor portion of the circuit are ok , that leaves the speedo itself. BEST to TEST first! Good luck.