I left my PC turned on last night, in Windows session, and when I returned home it was off (I guess it was because of hibernation). So I turned it on again, logo of BIOS appeared as usual, GRUB options appeared as usual, but then, whether if I click on Windows or Ubuntu, the result is the same: A black screen and nothing happens after.
I have discovered that I can log into Ubuntu if I go to "repair options" and click on update grub option, but just once, because once I reboot PC, the same happens again. If I try to access Windows partitions while in Ubuntu, it says that they are hibernating (I had to do some process I can't remember to allow Ubuntu recognize them though).
I have tried reading about similar problems, but they all suggest logging into Windows and turning off hibernation, but I can't log into Windows.