Hi Manuel,
Thanks for reaching out and thanks for using Crio Pro WordPress theme!
You’re issue is more than likely caused by a corrupt Permalinks structure. What you should do is navigate from your dashboard to Settings < Permalinks then just scroll down and click save to rebuild your permalinks. Be sure to clear your cache then check your category links on your website to see if the content is restored.
I hope this helps. Be sure to reach back out if you have any other questions.