now right click in right side pane and create DWORD Value (blue color)
Rename it as "NoViewOnDrive" (for locking drive) or Rename it as "NoDrives" (for Hiding drive)
double click on it and put some numbers to lock ur desired Drive and click ok.
DRIVE NOS. FOR A : 1 FOR C : 4 FOR D : 8 FOR E : 16 FOR F : 32 FOR G : 64 FOR H : 128
finally restart or log-off the computer to take effect.
Keep in mind that "0" is Default Value to Disable or remove this setting..
After locking the drive when u try to open it, u will see a msgbox like this "This operation has been cancelled due to restrictions in effect on this computer. Please contact your system administrator"