In cases where the Foxit PDF Editor icon on the bottom toolbar is shown as open, but the actual Window is not on screen, please check the following with the user:
Does the user often use an additional monitor and switch back and forth between using an extra monitor and just one screen?
Does the user use a virtual environment such as Citrix?
Please check the display settings to make sure that the system does not think there is still an external monitor connected
Then please navigate to Registry Editor on the machine.
Search for the following paths and delete:
Relaunch Foxit PDF Editor and the window should open up on the proper screen