Can't sign in on a bleep/easy2touch ts 700

Hi,

Hope someone can me please or at least stop me pulling my hair out. We have had our till for a good while now and has worked without a hitch until recently. We showed one of our employees how to update prices and add new items to the till which proved very helpfull to us but she has now done something and has effectively locked us out of the till by somehow removing the signing on screen. We see all of our products on the screen when it boots up and checks for network etc. and they beep when touched so we assume the screen is ok, but it asks us to sign on but the screen which did come up for this (to enter log on codes) has completely dissapeared so effectively locking us out of our own till.........please help...we now only have a very expensive paper weight and chewed finger nails....we have tried plugging in a keyboard, going into bios etc. but we cannot OR do not know where or how to remedy this problem, we have no USB stick/CD/ or anything of that nature to boot from to restore, is there even a way to reset the software to a factory fresh setting?? I have programmed the till once so i could do it again(Oh my God)....PLEASE HELP....we understand the till is also made under the easy2touch banner

Many thanks

Scott