Can't Access wp-admin

you can try and contact your host via live chat? they will sometimes help you troubleshoot these kind of problems and they have the advantage of seeing all your folders and files, etc.

I would suggest the following:

1. Make sure all of your plugins are deactivated (https://www.wpbeginner.com/plugins/how-to-deactivate-all-plugins-when-not-able-to-access-wp-admin/). Same with your theme. Rename your current active theme to disable it, and have it fallback to a default WordPress theme.

2a. If your site works after disabling everything, gradually re-enable your theme and plugins one by one. If the site breaks when you re-enable something, then you will know it is a plugin or theme issue.

2b. If disabling your theme and plugins does not resolve your issue, do a manual reinstall of WordPress. Step by step here: https://codex.www.ads-software.com/Updating_WordPress#Manual_Update . Once you have a fresh copy of WordPress reinstalled see if you dashboard works.