I was trying to upgrade the video card on my dual boot workstation and it stopped booting -- no grub menu, nothing. Windows was the original OS, Ubuntu came after. I put an Ubuntu 20.04 live CD in it and ran the boot-repair instructions per the second option. I'm quite grateful that the machine now boots Ubuntu, but there's no grub menu. If I hit the shift key, I can see a grub menu but there's no windows option at all.
Here is my boot-repair
pastebin: https://paste.ubuntu.com/p/kYR8MsgB4Y/
I think the Windows 10 installation is on sda.
Can anyone tell me how I can get the Windows 10 boot option back? It would be a real downer to have to reinstall the OS -- and I'd likely lose a lot of old software that is very useful to me.
EDIT: Thanks to Eric^^ in #ubuntu IRC, we have tried to get to the bottom of this. It would appear that something wiped the windows partition or something at some point (was this boot-repair???). There appear to be vestiges of numerous now-defunct partitions on the drive. I had repartitioned it quite a few times, and never really filled it up enough to over write the sectors. The TestDisk output tells a pretty sordid story, but doesn't give any indications what might have wiped the boot or killed all the data.
sudo update-grub
– oldfred Apr 22 '21 at 12:51