Calling for help from any Garmin Experts!!

Can anyone help? My Garmin 705 has suddenly stopped recording distance whilst I'm out on a ride, the screen shows the map and speed but distance remains at 0?. I've just downloaded todays route into Map My Ride and there's nothing to see at all! Its been in the box for about 3 weeks, when I put it away it worked perfectly .... any suggestions would be very welcome as I'm baffled

I would be intrested knowing how these work aswell,Mine is still for sale cheap if anyone wants one still?
I have instruction book etc if you want to borrow anything

Sara not stating the obvious but when you press the button do you get "timer started"? The garmin will show speed and all the rest of the gubbins but not record distance until timer started.

Failing that, turn it off, remove any micro sd card and turn on. Hold down the left button for over 3 seconds to reset, then try pressing timer start again - check if it records then.

If you think it is a fault contact Garmin in Southampton - very helpful team

Thank you for that I did the reset and it seems ok now, well, it measured my walk to the end of the road and back anyway .... I'll give it another go on the bike at the weekend