emachines g640 keyboard layout problem

looking for some help as we have exhausted all options we can think of.

first of all i apologise for the lack of capital letters, this will become clear as i fill you in.

got an emachines g640 from argos last january. in december, for unknown reasons, the harddrive decided to die. went back to argos for 3 weeks, new harddrive fitted, windows 7 re-installed (no updates though or appropriate drivers from emachines website).

got it home, mouse wouldn't scroll and keyboard layout appears to be wrong.

mouse: fixed by downloading the touchpad driver from emachines.

keyboard: left hand shift key acting as a help button, bringing up help window each time it is pressed. right hand shift key acting as a caps lock. alt button not working with all keys, some uppercase characters like ! not working either (thank you character map).

tried uninstalling, reinstalling, checked keyboard set for uk, tried changing it to usa, did not change anything. tried finding a new driver, non seem to exist - current one from microsoft is from 2006.

did a bit of googling and found a few threads relating to something i suspect has happened when it was being repaired and that is that the engineer connected a ps2 mouse and keyboard when working on it. a couple of threads mentioned that the keyboard issue could be something to do with the number lock from the ps2 keyboard.

tried connecting a keyboard and switching on and off the numbers lock and it has made no effect.

i should add that throughout the device manager has listed the keyboard as a standard ps2 keyboard, even before i connected the one i have.

argos say they think it is either a faulty keyboard or motherboard. i really don't want to have to send this away for another 3 weeks, maybe more. anyone have any suggestions?

thanks in advance.

i don't have a windows 7 disc, came pre-installed on the laptop straight from factory.  i did take recovery discs from it right away though.  have tried to restore or repair from them and they now fail to find a partition.