LabView opens windows for a VI's front panel and diagram in the locations at which they were last saved. It sounds like the VI you're having trouble with was saved to a location off the screen, maybe on another computer with a different screen resolution.
When you maximize a window, it's displayed to fill the visible screen, regardless of the original window position. For any Windows window, you can't resize the window when it's maximized. You have to Restore it before you can resize it. But for you, the restore puts it back off the screen where you can't see it.
Normally, in Windows, you move a window by grabbing its title bar with the move and dragging it around. If you can't see the window, you can't use the mouse to move it. But you can use the cursor arrow
keys to move it.
1. Left-click on the task bar button for the VI so it's depressed. Left-click on the task bar is a toggle button: click once and the window is displayed; click again and it's minimized. The task bar button will be depressed when the window is displayed and raised when it's minimized.
2. Right-click on the task bar button for the VI and select Move.
3. Press and hold each of the cursor arrow keys, one at a time, and watch for an empty rectangle to move across the screen. If you don't see a rectangle after holding one cursor key for about 5 seconds, try another key.
4. When you see a rectangle on the screen, press Enter and the window will be displayed.
5. Save the VI with the windows in the desired position.