Fortunately for us, actual scientists with degrees from places other than YouTube bothered to look into it, and they have found these claims to be utter bullshit.
If CERN managed to conjure up enough science-magic to create a black hole, it'd have a lifespan barely measurable in nanoseconds. Thanks to a little-known thing called Hawking radiation, black holes emit a type of radiation that causes them to lose mass and power as time goes on, an effect that worsens the smaller they get. In effect, the black hole would evaporate shortly after being born. That is, of course, if the sheer act of being birthed didn't cause it to be ejected into space at the speed of light. Which it would ... unless it was stopped through a billion-to-one-chance collision with another particle.
So ... let's assume that everything we've just said doesn't happen, and we're left with a black hole threatening to swallow the Earth like the house at the end of Poltergeist. We'd be screwed, right? Well, not exactly. Any black hole caused by CERN would be miniature (as in nano-sized), meaning it would have no significant pull or mass. In fact, in a worst-case scenario, it would take billions of years to grow to a point where it would start even slightly bothering us. It's questionable whether or not the human race would even be around to see this, let alone any of us.
"Whatever, Fallout 3745 just came out on NeuroStation."