Hi there Rosie, and welcome to the OM forum here to you too!Most pedometers I've had just had a very simple reset button on them someplace or other. I thought that one had a reset button on the extreme bottom left of the unit too. If you don't have the hanging-pack packaging display card it was bought on, or even the little instruction leaflet, then you could look at such in a nearby shop perhaps that has these. Or email Hi Gear even maybe, to find out what to do perhaps here.
Any joy on this problem at all then, Rosie. I ust thought I had better add that Hi Gear is to be found online at www.higearleisure.com rather than at just Hi Gear, as that address is taken up by a US machinery company, so folks tend to often find the outdoors company harder to locate by Google search etc. Just in case this might help you there maybe.