Android Question Screen orientation

Have a look at the Activity life-cycle video.
When the orientation is changed, the UI is destroyed and reconstructed so you have to save current state for components that need it (in your case the button text and, eventually its Tag property). Searching the forum you'll find a ready-made solution for saving/restoring items state.. StateManager

Note that StateManager only saves the user related state. It will not store the button's text. You can use StateManager with ToggleButton or just maintain the state yourself with a process global variable.