I have a Dell Inspiron 5000 with Windows 10 preinstalled. I attempted to install a Linux distro (OpenSuse 42.2) on it (dual booting), but now the BIOS will not recognise my hard drive. I should note this is my first time dealing with UEFI, so I'm a fair bit out of my depth here. I'll list everything I did.
The bootloader would not recognise the DVD drive with the Linux DVD as a bootable device, so I went to the BIOS settings and disabled secure boot, enabled legacy option roms and finally changed the boot list options from UEFI to legacy. I was then able to boot from the Linux DVD and install to a new partition. When installing I left all bootloader settings default. I noted that it used Grub2 and not Grub2-efi.
Upon rebooting the computer couldn't find any bootable device; it went through to some diagnostic checking. I rebooted to the bootloader menu, and under the Legacy heading I was able to select my hard drive which launched Grub. However Grub only showed options for OpenSuse, nothing for dual booting Windows. So I went back to the BIOS settings and changed the settings to how they were before: UEFI, no legacy and secure boot enabled. When I then rebooted to the bootloader menu the legacy heading had vanished along with all options to boot from the hard drive.
I went to the BIOS settings again, and in Boot Sequence the boot sequence was completely empty. So I clicked "Add Boot Option" to add the hard drive as an option. However an error dialogue popped up saying, "Warning: File System Not Found!" This error persisted whether I enabled legacy, UEFI or secure boot.
I now have a computer with Windows and Linux installed on separate partitions, but I can only boot to Linux and only if I manually go to the bootloader menu when the BIOS is in legacy mode.
Is there any way to restore my BIOS to boot to Windows?
I have a backup of documents and so on, but not of the entire hard drive prior to my fiddling with the BIOS.