|As RAID arrays go, RAID-0 is a very poor choice for a home user. If one drive fails, all data is lost & there's little chance of retrieving it. If you take it in for servicing, I doubt they'll even attempt to retrieve any data...they'll just do what has to be done to fix it (such as replacing the HDD's), reinstall the OS & send it back.|
Since one drive is apparently failing, the only way to convert would be to remove the bad HDD, reformat the other one & reinstall Windows from scratch.
Tell her to back up her important data immediately before it's gone for good.