HOW do you unlock file on a MacBook which is on a locked disc?

To unlock a file on a MacBook that is on a locked disk, first, ensure the disk is connected to your Mac. Open Finder, locate the locked disk, and right-click (or Control-click) on it, then select "Get Info." In the Info window, look for the "Locked" checkbox and uncheck it if it is selected. If prompted, enter your administrator passWord to confirm the change.