Modified system reserved partition but now no boot device found error(code:0xc000021a) on dual boot system(Windows 10 & Ubuntu LTS 18.04)

I actually tried to modify the system reserved partition size so that the recent windows update can be installed without error on my hp 15ac122tu machine which is i3 5th gen.

I tried to modify the size using mini partition tool by creating 500mb unallocated space and expanding the system reserved partition with that unallocated space. After the operation, the system falied to boot into any of the operating systems (my machine has ubuntu 18.04 LTS and windows 10 installed using dual boot) .

I think the problem occurred beacuse the modified system reserved partition is not recognized at the time of boot. I tried using diskpart utility, dism, scanning file system using the cmd at advanced options.

I have a discussion on windows forums. Please have a look at it Here. I tried everything they said except the rescue install but the issue still exists. So I'm asking here.

Here's some useful information about my system's disk & partition. Link Here

Note:

(This description is about the images in the above link. Please refer them)

Partition 1- System Reserved(This is the one which I modified)

Partition 2- C drive

Partition 3- Recovery drive

Partition 4- D drive

Partition 5- Swap Space for Ubuntu

Partition 6- Ubuntu Disk

Partition 7- E drive

Please help me to get out of this. Any help will be appreciated.

Thanks in advance :)

Edit:Please consider reading the comments as well to resolve this problem :)

You can now only boot from external media, so you should backup your files, possibly take backup images of your important partitions. I would really recommend taking a backup image of the entire disk, in case there is some problem with my theoretical procedure below.

If you can manage to access the contents of the UEFI partition (by assigning it a drive-letter), then take a backup of its contained files as well, because this can save you some time in resetting your dual-boot.

First, delete the resized partition using the tool of your choice.

Create a boot media for Windows of your version and boot into the Command Prompt and enter:

diskpart
List disk
Select disk X       (disk number of the disk)
create partition EFI size=xxx    (your current size in MB)
list partition
select partition N  (the EFI partition)
format quick fs=fat32 label="System"
assign letter=x     (some drive-letter)
exit
bootrec /fixboot
bcdboot C:\Windows /s x: /f ALL

Reboot your computer to see if it is fixed. If this works, you will only be able to boot into Windows.

You may return the previous contents of the UEFI partition and check if you can now dual-boot. Finally unassign the drive-letter in Windows Disk Management.