If you have not done this manually, this could happen due to a software or hardware error. You can resolve this problem in several ways;
Log into Windows > Start > Run / Search > Type “Command” > Type “Lock sys:on”
This will unlock your ‘C’ drive, if you want to lock this drive you can put the command as “Lock sys:off”
If this is for another drive, follow the same procedure but replace the drive name instead of ‘sys’
In addition you can check the BIOS settings whether this feature is available. In some BIOS, settings allow this facility
Also, check the jumper settings to unlock and lock the hard drives. Some drives are having this facility.
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