From time to time, Magento really screws up. You might find that suddenly, all your products 404, or category pages go missing.
Sometimes, a quick re-index works out the issue. Sometimes, it doesn’t!
So, what do you do? The best thing to do is to clear the DB, and reindex so Magento only has one thing to do at once!
- Connect to your Magento database (using your program of choice!)
- Find the table named ‘core_url_rewrite’ (it might be prefixed!)
- Truncate this table
- Log back in to the Magento backend and reindex all