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I have just installed Ubuntu 18 on my Asus ROG I also have windows 10 on my hdd (and also had id before ubuntu). After installing ubuntu I had some problems getting grub to actually show up and let me choose which OS it should boot into.
Now, when I try to boot into windows I get a black screen with a blinking cursor. but fortunately I can still boot into ubuntu.
I could also mount the windows partition and see that is intact, so the OS still is there.
My question is how can I repair the windows bootmanager (i think this is the problem here) from ubuntu. Thank you!
I have also downloaded a windows 10 iso image and wrote it on a usb stick, but when I try to boot from the stick, it just freezes and the asus logo remains stuck on the screen.