[ubuntu] blank screen with white cursor blinking

Hi all!

I've found a problem with my OS. Yesterday I found it with a blank screen and and white cursor blinking (pc was tued on). I restarted it and after BIOS, now I always see this screen, I don't see the grub and it stays there forever.

I followed instructions to recover the grub with the Boot-Repair, using the Live-version of Ubuntu with an USB stick, but it didn't work.