If all dialogs have disappeared hit the Tab key on your keyboard, it acts as a toggle switch
If it's only the tool options on the top menu go to Windows ➤ Dockable dialogs ➤ Tool options
You can also check Windows ➤ Recently Closed Docks ➤ Empty/or your recently closed docks are in there
If it's only the tool options on the top menu go to Windows ➤ Dockable dialogs ➤ Tool options
You can also check Windows ➤ Recently Closed Docks ➤ Empty/or your recently closed docks are in there