try to check your database.settings table
inside look for the extension_enabled
, can you see any value?
default installation must have ["flarum-bbcode","flarum-emoji","flarum-lang-english","flarum-flags","flarum-likes","flarum-lock","flarum-markdown","flarum-mentions","flarum-statistics","flarum-sticky","flarum-subscriptions","flarum-suspend","flarum-tags","flarum-approval"]