We don’t usually prefer to lock our drives, but sometimes it becomes nesscary. Say for instance you might have stored your office documents in D:\ and you don’t want your kids to access it, or you own a cyber cafe and you don’t want user to access the specific or system drive, in such case this technique can be useful for you. Please don’t try this tweak with your root drive (usually C:\ is the root drive) since root drives are not intended to be locked because they are mandatory for the system and application programs.
Start & Run and type Regedit to open Registry editor
Browse HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
Create a new DWORD value NoViewOnDrive and set its value as 2^ (Alpha Number of Drive Letter-1) where Alpha number are simple counting of alphabets from A to Z as 1 – 26

For example: to lock C:\, Alpha number of C is 3 so 2^ (3-1) = 4 (decimal value)
To lock more drives, calculate the value of each drive and then set sum of those numbers as value
To unlock your drive just delete the key from the registry.