a strange thing happened to the website. Without any human intervention, a huge number of products (or maybe all of them) changed their id numbers. So now all the items open in different URL address. We discovered it, because lots of Crawl Errors started to appear in Google Webmaster. For example let's take this ULR which appears to be not found.
If we search it in Google we can open a cached versión of the page. So this product is DZ-631. Angelfish Charm Pendant 14k Gold. Then searching DZ-631 in catalog we find out that this ítem is existing, but somehow has different id, so it opens in different address now:
Magento version is 18.104.22.168
Please help to understand how it could happen and what can I do to fix it