If the bootloader is fine but files are corrupted, use these integrity tools: sfc /scannow /offbootdir=C:\ /offwindir=C:\windows with your actual OS drive letter). DISM Cleanup: dism /image:C:\ /cleanup-image /restorehealth Microsoft Learn Step 5: UEFI/GPT Specific Repair For servers using instead of BIOS: to find the EFI partition. Select that volume ( ) and assign it a letter ( assign letter=S Exit Diskpart and run: bcdboot C:\windows /s S: /f UEFI is the OS and is the EFI partition).
Insert the (DVD or USB) and boot from it. windows server 2012 r2 boot repair