Entire Website Showing 404 Error

My entire website is currently showing a 404 error, despite my app functioning correctly. I cannot pinpoint when this issue began, as I am unsure if it appeared immediately after an update or some time after. There have been no recent changes or updates to the website, so I'm at a loss as to what could have caused this issue.

Ideal Skills and Experience:
- Expertise in website troubleshooting and debugging
- Familiarity with 404 error and its potential causes
- Experience with server-side diagnosis
- Ability to provide solutions to restore website functionality