no base game worlds showing in main menu, any advice please?

Try this: Delete the EA Games The Sims 2 folder. Start the game again to see if all the hoods generate. Enter the game to enable custom content if you intend to reinstall any or any later. Quit, start the game again, hopefully everything gets installed this time. You never have to uninstall or reinstall, just delete The Sims 2 folder and it should all regenerate.