Rename your plugins folder temporarily to disable all plugins. .
If necessary, also rename your active theme’s folder, then upload WP core.
Then reinstall WP manually (unzip to local, then upload) – saving your wp-config.php file first
That should get you access to admin. Then follow the steps here to clean up your site: https://wordpress.stackexchange.com/a/415705/29416
Then add fresh copies/installs of your theme and needed plugins (don’t copy the old ones).