radio only works intermitently . speedomiter doesnt work
With an 18 year old Nissan, I’d replace everything between the bumpers, that ought to do it.
Or, use 1960s tech, hang a transistor radio from your rear view mirror, ignore the speedometer. Drive with the traffic flow.
Ask your shop for a battery/alternator test. Check all the fuses. If that’s all ok, radio probably is simply busted and needs replacement. Speedo problem could be the vss sensor has failed. If you have an automatic transmission, are you noticing any weird shifting problems?
You can have the radio replaced at a car audio shop. The speedometer issue could be a wiring problem, a bad speed sensor, even a bad body control module. Best to have a hands on diagnosis.