Some of this is fine to check yourself. If the door's stuck, look at the track for anything obviously bent, check the photo-eye sensors near the floor for a blinking light, and see whether the springs - the coils above or beside the door - look intact or visibly separated. That much is safe to look at with the door powered off.
What isn't safe: touching a torsion spring under tension, or an extension spring that's stretched and holding a door's full weight. These aren't overstated warnings. A torsion spring stores enough force to break a bone or worse if it unwinds uncontrolled, and the tools to do it right - winding bars, a proper vise grip on the shaft - aren't things most garages have lying around next to the paint cans.
If the cable's frayed but the spring's intact, and the door's light enough to lift by hand without strain, you can get it up and blocked with a clamp to keep it there until someone gets to it. Beyond that, this is a call, not a weekend project.