What if a password-protected folder cannot be opened after unprotection?

Please choose a best solution according to the specific situation below:
1. Access is denied. There are two cases.
(1)This may be Access Permissions issue of the folder, and you need to change permissions.
(2)The folder is encrypted using the system built-in EFS and later replace computer or resintall system. If it's the former, please decrypt the folder on the computer where you encrypted it. For the latter, import the encryption certificate if you back up it. If no backup, there is no way out.

Readers also visited here: