Can't boot Windows 10 after messing reserved & installation partitions

I removed Windows 10 x64 (1809)'s 16MB reserved partition located just before the installation partition (which I then resized to be 84MB smaller, with the 84MB unallocated space at the beginning) and increased the SSD's EFI partition, which was located just before the reserved partition, by 100MB (by adding these 16MB+64MB).

I also kind of destroyed the EFI folder on the EFI partiton by accidentally replacing the entirety of its contents with other ones (I actually wanted to add the latter, not replace existing ones), so I no longer have the Windows bootloader.

I installed Ubuntu after all this happened and, sadly, not even GRUB sees my Windows installation..

I'd really appreciate some hints on how to regain access to my Windows installation.

Some things I tried so far (I ran them from a Windows 8.1 Installation DVD, since I didn't seem to have a working Windows 10 DVD):

The commands

Code:

bootrec /ScanOs
bootrec /RebuildBcd

Both detected 0 Windows installations.

The command

Code:

bcdboot c:\Windows /l en-us /s x: /f ALL

gave me the error 'Failure when attempting to copy boot files.'

NOTE: I also posted this same question on these websites, but so far have not received an answer other than reformatting my entire HDD, which is the last thing I want to try:
Cannot boot Windows after removing reserved partition and resizing installation partition - Super User
Can installation - Microsoft Community

Hi,

Thank you for your advice, I should probably give the software a look when I have the time.

Sadly, I did assign the letter to the EFI partition.

I ended up reinstalling Windows in the end, I really wish I had done that from the very beginning since I spent most of yesterday trying to fix it.