I have a dual boot with Ubuntu and Windows and somehow I wasn't able to enter Windows and grub rescue appeared.

I entered 'set root=(hd0,msdos4)/@' and 'set prefix=(hd0,msdos4)/@/boot/grub' as I found on q&a board. After I entered 'insmod normal' but there was an error. I rebooted and could enter Windows at this point. I then tried to enter Ubuntu but it was some error telling "can't read outside hd0" iirc. I read that I also need to update grub, that's why I was trying to get in on Ubuntu.

I figured I set it too narrow for multiple systems so I went and entered in grub rescue 'set root=(hd0)', 'set prefix=(hd0)/boot/grub', and then 'insmod normal', 'normal' without any errors this time. After this I did a reboot and now facing 'Read error' not being able to enter grub rescue again. I'm trying to recover it in terminal from USB now but I believe I can only see my USB drive from there. Here is the boot info I got: https://paste.ubuntu.com/p/9fY5w3gnXT/ with flash drive in. My HDD is 500GB which is not displayed. It displays in BIOS though.

What should I do?

Your post is unclear, are you able to boot into windows? The bootinfo script doesn't see your harddrive. A setting in your bios may have changed, a loose hard drive connection, or your drive may have died.

Resolved by hard changing sata port.