A. If you backed up the local EFS recovery key to restore perform the following:

  1. Logon to the computer as the local Administrator account
  2. Move to the directory containing the recovery key (it has a .pfx extension)
  3. Right click on the file and select 'Install PFX' from the context menu
  4. The Certificate import wizard will start, click Next
  5. Click Next to confirm the file and folder
  6. Enter the password used and click Next
  7. Select 'Place all certificates in the following store' and click Browse
  8. Select 'Personal' and click OK
  9. Click Next and then select Finish
  10. Click OK to the confirmation box

For other methods see KB article Q242296