cd c:\windows\system32\oobe
msoobe.exe
Make a generic account and password.
Hit finish (if it requests a product key and you have one, enter it now. if OEM/No key required, just finish).
Set time/date.
Finish.
grub rescue> set prefix=(hd0,1)/boot/grub2 grub rescue> set root=(hd0,1) grub rescue> insmod normal grub rescue> normal grub rescue> insmod linux grub rescue> linux /boot/vmlinuz root=/dev/sda1 grub rescue> initrd /boot/initrd.img grub rescue> boot