404 issues

Hi! Up until this morning, my site was working perfectly after moving it from staging to production a week ago. All of a sudden early today, I was receiving emails from Google stating an overwhelming amount of 404s were found. This includes a lot of new content that’s been posted since the new launch a week ago. I had changed a lot of slugs during the redesigning phase but have “Redirection” on my site. Otherwise, I haven’t changed any of these settings. However, content that never had its slug changed doesn’t seem to be working either. Can someone assist.

https://themusicuniverse.com

I can supply FTP credentials privately, upon request.

Thank you,
Buddy