kelthic is correct, that driver is standard within windows, but we still dont know which model she is on. http://www.dell.com/support/drivers/us/en/19/DriversHome/NeedProductSelection
let dell detect your tag number (model), go to the downloads/drivers section, MAKE SURE YOU CHOOSE THE CORRECT OPERATING SYSTEM, and then go to the input section. if there is no keyboard driver, and only a touch pad driver, then they are bundled together. some do it that way, some dont.
download the touchpad driver. install.
if that doesnt work, then try system restore. if that doesnt work, then you have a hardware problem and need to take in or sent in for service.
hope that works !!!