1. If Hidden Files are locked and you cannot see them then us this method to UN-hide them:-

• Go to registry editor by running regedit in the run box from start menu.

• Go to this key:
  HKEY_CURRENT_USER\Software\Microsoft\
  Windows\CurrentVersion\Explorer\Advanced
  
  In the right hand area, double click hidden and change the value to 1.

2. If Registry editor is locked or is not opening then us this method:-

Easiest way:

Select all the codes below. Copy (Ctrl+C) and paste them (Ctrl+V) in the Run window from start menu.

Press enter, and there you are!

REG add HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v

DisableRegistryTools /t REG_DWORD /d 0 /f

Then write regedit in run window and regedit will be open.

3. If Task Manager (Ctrl+Alt+Del) is locked or not opening:-

   a.  Click Start, Run and type Regedit
   b.  Navigate to the following branch:

HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Policies\ System

   c.  In the right-pane, delete the value named DisableTaskMgr
   d. Close Regedit and its done.