The LockWorkStation function submits a request to lock the workstation's display. Locking a workstation protects it from unauthorized use.
This function has no parameters.
If the function succeeds, the return value is nonzero. Because the function executes asynchronously, a nonzero return value indicates that the operation has been initiated. It does not indicate whether the workstation has been successfully locked.
If the function fails, the return value is zero. To get extended error information, call GetLastError.
Common reasons the workstation might not be locked even if the function succeeds include the following: no user is logged on, the workstation is already locked, the process is not running on the interactive desktop, or the request is denied by the Graphical Identification and Authentication (GINA) DLL.
This function has the same result as pressing Ctrl+Alt+Del and clicking Lock Workstation. To unlock the workstation, the user must log in.