Hi,
did you change the "language" of Virtuemart and Joomla? (from English to some another language?)
Because products (that comes with SportMart QuickStart) are added for English language, if you browse the front-end with a different language (or if you change the default language) the Virtuemart products and Virtuemart categories will give 404/not found error. Because those are meant to be seen only for English.
- Delete all the VM product and VM Categories (don't just change their names, delete them completely)
- Create your own VM Category and VM Products from scratch (make sure you are seeing your language's small flag at the top while adding VM Category and VM products)
Do the same procedure for Joomla Menu Items as well, because joomla menu items are also language specific.
Regards,
Support