I purchased a Nissan caravan KG VWE25... From Japan it was at 230 000km on the dashboard. After another 30000km the speedometer stopped functioning. The dash clock still shows the mileage but speedo no longer moves.
If the odometer is still working and the speedometer isn't, It could be a malfunction in the instrument panel where the cable comes in to it.
If both is not working, could be the cable, or the plastic gear that is attached in the transmission.
I did not get the year of your vehicle, so I am making an educated guess.
Hope this helps -