I have an Asus vivobook s400 which came with windows 8 installed. When the windows 8.1 preview was released I installed it to check it out. However when I tried to reset it to factory conditions it said that some files were missing and asked me to insert recovery media even though my laptop has a recovery partition from Asus. I put a windows iso on to a usb drive and it worked. But it had installed a fresh version of windows 8 and not the Asus one with all the drivers and software. How can I make it reset from the Asus partition?