How to fix “Invalid Disk” error in Windows 7

If you have ever plugged in an old drive and the disk management said it was an invalid disk. Then this may help.

  1. Download HxD its a free Hex editor. 
  2. Install and open the problem disk by clicking “Extras” then “Open Disk”
    - Make sure you open the right disk! your disk management will list your disks starting with 0, this tool will start with 1
    -  Also, the default option is to open the disk read only, your going to want to uncheck that when your ready to fix your “Invalid disk”.
  3. Scroll down to offset 1C0(the row) and look in the 02 column. that cell should read “42″ which means Dynamic disk, Change it to “07″ and save changes. 
  4. If your using an external drive unplug it and plug it back in otherwise reboot your computer.
  5. That should have re initialized the disk and it will now be readable. 
  6. If not go into disk management and take the disk offline then bring it back online. 

Doing this will result in No Data Loss!