I have 2 disks. I have Windows 10 on SSD and recently installed Linux on HDD. After installing linux, the windows boot option in uefi disappeared, instead a cd / dvd option appeared. I don’t have a CD player or something. There is no windows option in grub either. And in Manjaro, only my HDD is shown in the application with disks. Anyone had a similar problem?
Try in terminal:
sudo xed /etc/default/grub (substitute xed for your favorite text editor e.g. mousepad, nano, etc.)
uncomment (remove the # sign) on the line:
save and close text file
then sudo update-grub
I suspect that Win 10 was in hibernation when you installed Linux.
By default, Win 10 goes into hibernation even when you click Shut down (how stupid is that?!). When in hibernation, the Linux installer can’t detect it.
The Windows 10 USB installer contains a Startup Repair tool which I think is worth trying. If that gets Win going again you can disable its hibernation and proceed to fix GRUB in Linux.
I am not saying that @jrichard326 is wrong, I am just showing a different approach.