Lost your Windows 10 Recovery Partition? Can’t run mbr2gpt?

Here’s how to fix it:

You will need Windows 10 Setup media to recover the WinRE.wim, if you don’t have this you can user

Media Creation Tool

To avoid the need for extra partitions, I used a folder c:\recovery

mount your setup media (iso or usb) 

in an elevated prompt run the following commands:

creating folders

md c:\recovery

md c:\recovery\mount

** mounting Windows Image from media

** (if setup media drive letter is not e: replace the e:\ with the correct driveletter)

dism /mount-wim /wimfile:e:\sources\install.wim /index:1 /mountdir:c:\recovery\mount /readonly

** Copying WinRE.wim from image

copy “C:\Recovery\mount\Windows\System32\Recovery\Winre.wim” c:\recovery\

** Unmounting Image

dism /unmount-wim /mountdir:c:\recovery\mount /discard

** Enable WinRE

reagentc /SetReImage /Path c:\recovery\winre.wim /index 1

reagnetc /enable

reagentc /info

** The last command should show RE enabled, after this I was able to successfully run MBR2GPT

also available here: answsers.microsoft.com