when i reset the trip milage both the trip milage and the odometer have stopped working

Sweet. Go on a trip!

my 96 pathfinder does the exact same thing...all i did was say screw and let it be, it does keep th value of the car up...after about 6-7 months mine started working again but not full strength, it will stop every now and then. since your trip milage stopped, your overall milage will also stop; it runs off the trip, so fix your trip and your odometer will be fixed.