Start Windows Explorer by scheduled task with elevated rights in interactive mode and SYSTEM account, Regards Milos

Hi , Could you tell me what action was done before this issue occurs? You may perform the system restore through system recovery options at boot. 1. Start or Restart the computer, press F8 every second until you see the Advanced Boot Options. 2. Select Repair your computer and press Enter. 3. Select your keyboard language preferences and click on Next. 4. Select your user name and type in the password, and then click on OK. 5. Select the System Restore option.Tracy Cai TechNet Community Support

seems this is the local administrator u have tried. if this system is under domain, can you please login with domain administrator and give full right access for local administrator to c drive. or else can you right click the C drive and go to security and then go to advance tab and give the administrator full rights.

By mistake our engineer have denied permission to c:\ drive so now not able open c:\ drive from any admin login also not bale to take ownership.