Hi!
This is a conflict with some other plugin. To solve it you need to disable plugins that may interfere. I use myself a lot of plugins without conflict problems. I don’t use the MINIFY plugin, which I saw that you use.
First of all: Clear the WordPress cache and see if that is enough.
If not, disable temporarily the Minify plugin. If Facebook now appears you need to configure Minify (or disable it permanently) in a way that solves the conflict. If Minify is not the problem, you need to repeat this check with other plugins.
If Minify is not the problem, to avoid checking your plugins one by one, you can send me a list of your plugins to let you know which of them are tested and are not causing any conflicts, so that you will have to check only a few of your plugins.
If I can do anything else to help, please let me know.
George