Unable to install grub, partitioning questions and bios not seeing drives

Installing Zorin OS
1

Unable to install grub seems to be the main problem now although when I go into my bios to boot to the USB drive it is no longer an option and many of my other drives have disappeared as well. I have booted to the USB drive several times successfully and if I don't choose to enter bios my computer boots to windows as default, even tho' I changed the bios to boot to USB as #1. Also the bios acts like it doesn't recognize the drive that windows is on either.
I know that's a lot to digest. I know it sounds paranoid but I believe windows (10 at least) actively fights against installing other OS's.

I should have mentioned my first error was not having an (efi ?) partition. So I created one but didn't know what size it needed to be, so I made it 600 Mb, just a little bigger than the one for Windows. That seemed to work for a while. I was 3/4 the way thru the installation when I got grub error.

2

Hey,
I think I fixed the grub issue with Boot Repair. Still might need to change bios settings and I'm not sure where to add the command that makes grub recognize my windows OS.

3

Welcome to the Forum!

Some Questions for Beginning:

  • Are Secure Boot and Fast Boot in BIOS disabled?
  • Is Fast Start-Up in Windows disabled?
  • Is Your BIOS in UEFI or Legacy Mode?
  • What Tool did You take to create the bootable Stick with Zorin on it?
  • When You install Zorin what Install Option did You choose? ''Install Zorin alongside Windows'' or ''Something else''?
4

Grub should automatically add an entry for Windows. You mentioned you created an EFI partition. My guess is the new EFI partition doesn't have an EFI folder for Windows. Is Windows installed on the same drive as the newly created EFI partition? IF Windows is installed on a separate drive and all partitions are still good (recovery, efi boot partition, etc...), you can manually add a grub entry for Windows if it's not getting detected. If somehow the efi partition for Windows is damaged, then not sure how you can get windows to work again without reinstalling it. Let us know and we might be able to assist you.