1)Thank You very match for attention to my problem.
2) When I power on my NUC, I see built-in EFI Shell interface, if i understand this situation correctly. Could You see to the picture, added to this message?
3) I try to use usb keyboards, wire and wireless.
4) My storage drive is WD Blue 500gb hdd, RAM is Crucial 4 GB.
5) yes, it is Windows 8.1
6) yes, it had been working after i had installed it. But after i rebooted it, the boot storage was undetected. I made changes to bios settings, including, by thoughtlessness, turned on the internal shell.
1. Press and hold Power Button for about 3 seconds. Count 1001, 1002, 1003,1004. Release the Power Button. NUC should reboot into Power Button Menu. You should release the Power Button before 4-sec shut down override or when the Power Button LED changes color from blue to amber.
2. Press F2 to enter Bios.
3. While in Bios, press F9 followed by "Y" to set Bios default settings.
4. Press F10 confirmed by "Y" to save settings and exit bios.
Hope this will help