i have speedo problems?

[billiam3po]

I have a 1993 nissian altima and the speedo registers through 15 mph and anything else the gauge sticks at 40 mph. the tach seems to work just fine. Also it does not register the milage anymore. i bought it used it worked intermitent ticks off 14 miles and stops and comes on for 20 more and now nothing. Plese help from anyone , my new job requires i document the miles and my car is F ed thanks anyone????????????