Google Hangouts window invisible

You can try two things.

Click on the Hangouts window icon in your taskbar. Then try Windows Key + Left or Right arrow (keep pressing them to continue moving the window). This may move the window to the left or right side of your screen, then you can drag it where you want.

You can also try this. Click on the Hangouts icon in your taskbar. Press Alt + Spacebar, then hit M, then click any arrow key direction, then move the mouse. The window should be attached to your cursor and you can place it where you like.

Try and practice these on visible windows first.

The answer from @natewin did not work.

However, Alt + Spacebar → x maximized the Hangouts screen into a viewable area, allowing me to drag it to center, resize, then re-place onto my desktop area.