If you don't see comments or buttons to share content on social media, check AdBlock's options to see which filter lists you're subscribed to. (To do that, click the AdBlock button in the browser toolbar and select Options, then click the FILTER LISTS tab.) You're almost certainly subscribed to either the Antisocial or Fanboy's Annoyances filter list (or both). Those lists block social media widgets that, among other annoying things, can track your browsing behavior.
If you prefer to keep those filter lists enabled, just click the AdBlock button in the browser toolbar, select Pause AdBlock, and reload the page. Comment or share, then unpause AdBlock by clicking the AdBlock button and selecting Resume blocking ads.