Accidentally overwrote UEFI-- How can I get the Windows 10 one back?

[AmyRoses]

Not 100% sure how UEFIs work, so I'd appreciate if someone could explain them to me or link me to an explanation- anyway, I accidentally overwrote my UEFI with another one, and now I have to F11 to select my boot partition manually. Is there any way I could restore this?

Thanks!

 

[Rdslw]

if you have DVD then "repair" windows should do the trick.

 

[AmyRoses]

if you have DVD then "repair" windows should do the trick.

Downloaded a Windows 10 iso, and there doesn't seem to be an option to repair this specific problem in the 'repair' section.

 

[Rdslw]

Windows install DVD have "repair all" button that would do this along a lot of other stuff.
This is tutorial how to do it step by step, I think you don't want autodetect as it likes to replace more stuff:
http://www.dell.com/support/article/pl/pl/pldhs1/sln300987/how-to-repair-the-efi-bootloader-on-a-gpt-hdd-for-windows-7--8--81-and-10-on-your-dell-pc?lang=en

 

[AmyRoses]

Windows install DVD have "repair all" button that would do this along a lot of other stuff.
This is tutorial how to do it step by step, I think you don't want autodetect as it likes to replace more stuff:
http://www.dell.com/support/article/pl/pl/pldhs1/sln300987/how-to-repair-the-efi-bootloader-on-a-gpt-hdd-for-windows-7--8--81-and-10-on-your-dell-pc?lang=en

So uh, that did a lot more harm than good

I followed the steps, but it said that it couldn't find the file path (paraphrased) when I got to entering 'cd /d <drive letter>:\EFI\Microsoft\Boot\'. Then I couldn't boot my PC up at all, and it turns out that my entire EFI partition was then completely wiped and formated as RAW for some reason. After reformatting it as FAT32 in Diskpart and naming it 'EFI' again, I'm pretty much back to square 1. I can still boot into Windows, but I have to manually select the disk. I'll try creating the folders in my EFI Partition and try again, I'll report back, thanks for the help

 

[AmyRoses]

Okay, so I did that, and now it obviously finds the file path, but the ren BCD BCD.old command fails.

 

[AmyRoses]

Final update before I get a reply, but I guessed that that step was only for backing up and that I'd lost it anyway, but the next step fails also; it acts as if there's a syntax error in the command, and just tells me what bcdboot does and how to use it.
Command is bcdboot 'c:\Windows /l en-us /s <boot letter>: All'

 

[AmyRoses]

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