The ID number you have mislaid is also stamped on the chassis of the unit, but unfortunately there is no other means of getting to know this without pulling the unit out of its holder to have a look at the the chassis for the number. You can reset the devices computer by holding "select" + "0/I/att" AT THE SAME TIME (which will erase all your settings) but its doubtful if this will restore the code as I am not acquaint with that model.