When you say you're unable to .. what do you mean? Are the buttons not there? Do you press them but nothing happens? Does it allow you to insert, but not show them?
Also if you can state the browser you're using (and any others that you've tried, with the same result), that would probably be helpful too.
Two things I've noticed ... Previously I've had an issue where formatting was off, and it was because I had my browser set to "zoom" in a little (there's a hotkey combination and I'd pressed it without realising) - so might be worth checking that. Secondly, currently we've discovered that, using Google Chrome browser, it does not show some images .. just the "broken link" type box (although if you right click and show image in a seperate tab, it works). Are either of those similar to your issue?