I would say "reinstall GRUB2", but you'll have Linux reinstalled by now since that's fast... oh well.
GRUB2 ah I was unable to fix it after few hours of googling and learning of grub rescue commands I decided to re install whole PC and got again corrupted windows 8 bootload but this time I was able to fix that problem with command line the problem was simple windows 8.1 is instaled in EFI as you wrote but xubuntu has installed in native boot mode but after that exertion I have nice and fully work dual boot
Great to see that someone can actually use google. If everyone could do that I wouldn't have had to write that guide. You don't actually fix GRUB with the grub rescue; you boot with a Linux Live DVD/USB, then use the chroot command to get the rights of the installed Linux's user account, then you reinstall GRUB. There is something you need to do during that which has to do with the EFI but I never had an EFI mainboard so I don't really know.
and another experience is that any update of GRUB broke windows bootloader than for all first update your grub to your likes and after that fix windows bootloader fixing your bootloader for windows is simple First of all, you will need a bootable disc or pen drive. Booting into the Windows 8 setup, select “Repair your computer” in the bottom part of the window, then “Troubleshoot” and “Advanced options”. If you have a restore point created you can go back to that working copy of the OS without losing your data. Well, I didn’t have any. Chose Advanced options and choose the Command Prompt. Going for the next easiest way to fix the problem, enter the following two commands into the prompt: bootrec /fixmbr bootrec /fixboot
You did not really have to do it, but it's a good way to get more people actually try it, because as you suggest it, you immediately hand them a guide to install it, so they don't need to search. And those who can't use google will probably not install it anyway, because when switching to a different (unfamiliar) operating system, the need to use google is guaranteed to arise soon.
