You can use any version of TurboTax CD/Download to claim an allowable business investment loss. You can also do this with TurboTax Online, but you would not be able to see the actual forms while you prepare your return. Also, typically only 3 years of TurboTax Online are available, while TurboTax CD/Download will remain on your computer unless you uninstall it.
If you're using a TurboTax Live product, you can select Live Help or Expert Help to connect with a TurboTax specialist.