After a very long and difficult Windows 10/Ubuntu 14 dual boot installation (the usual Nvidia/Nouveau compatibility issues), I finally have Ubuntu working, only to discover that Windows had disappeared from the (finally functional) grub menu.
sudo update-grub
couldn't find Windows. I added it as an entry in 40_custom and tried to boot it, only to get an error message that says: "the boot configuration data for your PC is missing or contains errors"
Windows Boot Manager
Windows failed to start. A recent hardware or software change might be the cause. To fix the problem: 1. Insert your Windows installation disc and restart your computer. 2. Choose your language settings, and then click "Next." 3. Click "repair your computer." If you don't have this disc, contact your system administrator or computer manufacturer for assistance. File: \Boot\BCD Status: 0xc000000a Info: The Boot Configuration Data for your PC is missing or contains errors.
So far I have tried: boot-repair MBR: completed without errors, did not fix problem bootrec: as above windows reset: The drive is locked this: file not found
I don't have anything actually installed on windows yet, so it's not a big deal to reinstall, but I don't want that to damage the Ubuntu install, because that took a really long time to get working. Is there anything I haven't tried yet that might work?