If you have a spare monitor or can connect to a TV, try plugging it in to see if the issue might be with your primary display. Sometimes the display output can get switched, especially in a multi-monitor setup.
If you can get into Safe Mode, try running sfc /scannow in the command prompt. This can fix any corrupted system files that might be causing the black screen issue.
If nothing else works, using the Windows installation media to run a startup repair might help. It could fix boot issues that Safe Mode and other methods can’t.
i would probably have to use some repair stuff, but would it keep all of my files and apps in the system or just overwrites everything? (on 1 partition?)
and would the repair stuff even work on a multiboot system? or i could later somehow update the grub on the disk via the live cd? or that would still mess up the windows bootloader anyway, so theres not even any point in grub update?
i think that the issue probably started again with resizing the partitions, because the 2nd 64bit system only "plays" a youtube video when u press the space bar very fast lol.... like it wont even play when you hold it down, only when u press it really fast, because as soon as u have pressed it once, it will automatically pause the video again..... and i think i had the same exact issue the last time, but i dont even have a clue what can even cause this and why doesnt it fix it with sfc scan.... (i even tried it in safe mode with even worse fuzzy screen, but it did not bring any of the picture back... but it did reboot the pc via the blind shutdown command, so it obv had to accept the sfc command too, because it should have admin rights in safe mode...)
it does not show anything, but i can do everything via the blind cmd commands etc, so everything basically works 100%, but it just does not show any picture lol (even when i try to press the Lcd hdmi buttons etc... and i'm not even sure if it even had any (external) display drivers before, because its 32bit win7)
so maybe someone can set up their own test system with 32bit, 64bit and linux multiboot and then try resizing some of the partitions with gparted via the live cd?