Answer to 'Shiggity' - How do you post a comment on Instructables? Answered
Same problem here.
Bear in mind that Instructables is based in San Francisco and that it's the middle of the night in the U.S.A at the moment. This is the time when the Instructables Robot moves the furniture around (commonly called 'system maintenance') so that Instructables is available when the U.S. wakes up.
Give it a couple of hours and you should find everything is back to normal and the 'comment' or 'answer it' buttons will work as they should.