Mary, I could be wrong about this but I think that it appeared that I also didn’t have an edit button one day–and then I realized that I had been timed out of my account. The page with the thread was still there but I think it had refreshed after I’d been timed out. I went to the “My Account” dropdown at the top right of the webpage, signed in again, and I _think_ that did it for me: suddenly I could edit again. Worth a quick try at least.