Speedometer problem please help

Hi I have a 1998 Mazda B3000 3.0 V6 5 speed manual transmission 4X4. Which we all know that it's a ford ranger with a Mazda name plate. Now for my question my speedometer quit working for about three days and now it's working again what would be the cause of this? None of the lights are on such as the check engine light or the ABS light. They never came on and this isn't the first time the speedometer did this it did this a few months ago as well. I would like to fix this but not sure what to fix. Any help would be great thanks.