Edit by Rick: this was split off from https://forums.getpaint.net/topic/31884-restoring-lost-windows/
Sometimes F8 doesnt work for some reason. And the icons are not found along the top right of the window. In this case Look across the top menu & click on 'windows'. Should be 2nd from the last. You will see the color wheel icon in the drop down. Click on it.. Voila!