nozzle too high when start printing

Hi,there Im new at this ,Im having issues when I home all axis it does what it is required and checked the clearance with a sheet of paper all set press print and it recalibrate moves to the print area lifts up 2mm and start printing at 1mm.by the way is is a geeetech I3 pro B with GT2560. I think I mucked up the with G Codes trying to set up a auto levelling
but I'm trying to set it back,so is there a way to reflash to get it back to default settings or any other ideas to fix the problems.
Geoff

Are you doing a G28 and G29 before a print? Does it still do it if you skip the G29 line?

I have switch off the auto bed lev and trying with the old method Z stopper and paper all set and homed and when you press print it raises a couple of mm and comes down waits a minute and start to print but to high.When I home or press G28 it goes back to the front right and to the correct hight again.
Geoff