So a little bit of backstory first: I originally ran a Ubuntu 18.04/Windows 8.1 Dual Boot setup and everything ran fine. But I was running into some problems regarding the space of my Ubuntu partition, so I decided to do a fresh installation of Lubuntu 20.04 to overwrite my old Ubuntu. All of the steps were successful and it installed correctly. However, after this I was unable to boot into Windows 8.1. Its filesystem was still present and I could mount it in Linux, however no matter what I did I could not get it to show up in Grub. After looking online some people recommended installation rEFInd but it wasn't finding Windows either.
Using the boot-repair utility, I got a message saying I had an installation of Windows in legacy mode(which I found out because I was booting in UEFI for my previous installation of Ubuntu and everything was fine). Trying to start my computer in Legacy mode just resulted in a black screen saying "No boot image found" or something similar .I booted a live USB and used boot-repair again,the details of which can be found here. After this I was able to boot my Lubuntu in Legacy mode but still no sign of Windows.
After this I tried using boot-repair again, grup-update and even defining a custom grub entry pointing to the partition where Windows was supposedly booting from. I tried all of these things in both Legacy and UEFI mode. I've tried just about everything I could find on the Internet but nothing worked.
My (admittedly uneducated) guess is that, while setting up the partitions during the Lubuntu install, I somehow messed up and erased/damaged something crucial to Windows booting. What I did during that step was, following the instructions, create a new root partition out of my old Linux partition and some unalocated space, as well as create an EFI System Partition(overwriting one pre-existing partition which I believed was the old Ubuntu's boot partition. If the fault is in the installation step, I'm almost sure it was due to this.
Here is the output of the output of the bootinfoscriptutility and below is the output of lsblk -f:
NAME FSTYPE LABEL UUID FSAVAIL FSUSE% MOUNTPOINT
loop0 squashfs 0 100% /snap/chromium/1479
loop1 squashfs 0 100% /snap/core/10823
loop2 squashfs 0 100% /snap/core18/1988
loop3 squashfs 0 100% /snap/gnome-3-28-1804/145
loop4 squashfs 0 100% /snap/gtk-common-themes/1514
loop5 squashfs 0 100% /snap/postman/132
loop6 squashfs 0 100% /snap/rustup/617
loop7 squashfs 0 100% /snap/snapd/11036
sda
├─sda1 ntfs Recovery 62107AA6107A80B9
├─sda2 vfat 4DF5-12AD
├─sda3
├─sda4 ntfs Acer 8C787EE3787ECC08 49,2G 88% /home/diogor/windows
├─sda5 ext4 3619ba7c-87d2-4f85-add7-e8890a226259 16,7G 55% /
└─sda6
sr0
Thanks in advance. If any further information is required I'll be happy to provide it.
