Yes button grayed out in User Account Control Windows 10 (fix) - How to

As a Standard User when i try to make changes to my PC, i am getting User Account Control Window stated with the following messages: Do you want to allow this app to make changes to your PC? Program Name: User Accounts Control Panel. Verified Publisher: Microsoft Windows. File Origin: Hard drive on this computer. To continue, type an administrator password, and then click Yes. But No password entering box is given and the 'Yes' but is disabled or grayed out. Unable to click 'yes' button.
Reason: You are Standard User and you don't have rights to make changes. You need Administrator rights to make changes. Also, Administrator account is disabled. When i try to enable, i am getting the message 'The following error occurred while attempting to save properties for user Administrator: Access is denied. OK.
Solution: How to fix - Enable safe mode and enter into safe mode. Open control panel and change your account type from Standard to Administrator.