More recent versions of Royal TS allows you to reset the layout through the UI:
- Open Royal TS.
- Open the "Options" dialog by clicking on Options on the View ribbon tab.
- Select "Troubleshooting" in the options tree.
- Switch to the "Reset Settings" tab.
- Check "Reset Dock Panel Layout".
- Click on the "Reset Settings" button.
- Restart Royal TS.
If you run into the situation where you cannot bring back the navigation panel, you can simply start Royal TS V2 from the installation directory with the /resetlayout argument.
[Royal TS installation directory]\rts3app.exe /resetlayout
The above command will reset the panel layout to the default setting.
Note: the installation directory may vary on systems depending on OS, language or custom installation path. To determine the installation directory, use the Royal TS link properties in the start menu.