Thanks esmi,
Fortunately, deactivating plugins has fixed the problem. The culprit was Foter, so removing it has restore the WP functionality and my faith in humanity, as well. 🙂 Thanks again.
Thanks endocreative. Unfortunately, I have no idea how to do this in my theme (Headway). Would appreciate if there is another, easier solution. Thanks.
Why? This is something that happened after I changed the settings for the WP plugin.