Updating anything sends me to a 404…

Alright so, I’m trying to add a new post, and when I am done I click Update.

I just added a new post the other day and it worked fine but now it is sending me to
https://www.66thieves.com/wp-admin/post.php once I hit update.

This isn’t just happening on posts, its happening on anything database related or so it looks… Updating permalinks, or anything in the site sends me to this error.

https://www.66thieves.com/wp-admin/options-permalink.php
Apologies, but the page you requested could not be found. Perhaps searching will help.

I added a new product to my Cart66 plugin, it adds items fine… Changing meta data in general settings works fine as well..

I’m not quite sure whats happening here.

Any help would be appreciated.