Press the "Menu" button on the screen and then use the other buttons to browse for a "Factory Settings" mode. Select this mode to reset the monitor to its original settings.

Here’s one that will let us fix our borked ASUS computer monitor buttons. [Silviu] has the same monitor we do, an ASUS VW202, and had the same problem of stuck buttons.

You should see a menu or a list of input sources appear on your screen. Keep pressing the button until you reach the input source that corresponds to your computer.