I can't figure it out. I even logged out (in Firefox) and looked at the posts, and the buttons aren't appearing, then logged back in, and my "Settings>sharing" page looks strange. It's been a while since I visited the sharing page, but I seem to recall that the little preview down at the bottom of the page that shows what buttons will appear actually shows the buttons, not just text (and I've chosen to have buttons, not just text, to appear on the blog).
Thanks for the link, as well, but that's not the problem. The FB like button that comes standard as an option in "sharing" has disappeared for me -- I can't even drag it away if I changed my mind about using it. Yet I know that it's on the posts, since when I'm on Opera, I can see a facebook like button.
Also, oddly, the link that I created myself for newsvine is still there on the settings>sharing page -- although I don't see its icon unless I hop onto Opera to view the page.
I greatly prefer using Firefox for this blog, since I use Opera for administering another blog under a different email addy, and I am able to stay signed in on both browsers with two different accounts for a number of different sites.
I did try a forced refresh, but that didn't fix it. I haven't done much with my blog recently because of various RL issues, so I'm a bit rusty with the possible fixes.