Everything broken :(

My site is displaying fine, but I can’t make any updates. For example, if I make an update to a blog post and save, the change is not saved. I also can’t upload media, or disable plugins (I try, but nothing happens).

I’m using the latest version of wordpress and I’m using Firefox on a Mac. I’ve tried using Chrome but I can’t login (no error, just reloads the login screen).

On the dashboard I see the following database error
INSERT, UPDATE command denied to user ‘XXXX’ for table ‘wp_options’

Any ideas?