Make and model of laptop ? If came with Windows 8, know if it has a recovery partition to reset back to factory settings when bought or did it come with a OS disc. ? Check in Disk Management, find link on Start button in desktop by right clicking, might show if there is a recovery partition, if so hopefully did not erase it or have a win8 disc.
No need for that. They just need the System Restore discs, that they should have made when they first got their system. If not, they will have to order them from the computer mfg.
This is why I always make a disc image, before swapping back and forth between OS's.