Skip to content

How to Fix Corrupted Bootloader After Installing New OS

Issue Description 

Installing another OS can overwrite the Windows bootloader, preventing Windows from starting. 

Common Causes 

  • Dual-boot misconfiguration 
  • Bootloader overwritten 

Step-by-Step Solution 

Step 1: Boot Into Windows Recovery 

  • Insert Windows installation USB 
  • Boot from USB 
  • Select Repair your computer 

 

Step 2: Open Command Prompt 

  • Go to Troubleshoot → Advanced options → Command Prompt 

 

Step 3: Repair Bootloader 

Run commands one by one: 

bootrec /fixmbr 

bootrec /fixboot 

bootrec /scanos 

bootrec /rebuildbcd 

 

Step 4: Restart and Test 

  • Restart PC 
  • Confirm Windows loads correctly 

Explore Further 

  • Repair EFI partition manually 
  • Reconfigure Linux bootloader 

Prevention & Best Practices 

Always back up before installing another OS.