Long story short had to change battery on my vrs reset the clock and the windows. But before it died miles left in tank said 85 the needle hasnt moved but cpu saying 50 miles now. But the warning light normally beeps on at 65 and has so far not come on. Do i have to reset anything else or is it a case of it will sort itself?

nope it will sort itself...

you must get good mpg so the computer calculates remaining miles on your recent mpg... as the car has reset itself it will be back to factory mpg calculations...

this will sort itself out