Slashfilm dug up two rumors around Luke Skywalker's role in "Episode 7." As with all rumors, they are unverified. Director J.J. Abrams has been keeping a tight lid on details about the movie's plot and characters.
The first is from a Star Wars 7 News message board and describes a scene in which Daisy Ridley's character meets Han Solo (Harrison Ford) and Chewbacca at a cantina:
The second, from JediNews, is very much in line with that, detailing how Ridley's character and John Boyega's character are looking for Luke Skywalker (Mark Hamill):
She is confronted by an alien, she lifts her blaster to him, he then takes it from her hand "Don't point a blaster at someone if you are not going to use it" and points it at her ...
Cut to the outside of the Cantina as a Planet/Moon is blown up outside, Han is present here (Wearing a thin cut, waist length leather jacket, boots etc, a "Matching outfit") oh and he still has his blaster
If these descriptions are accurate, "Episode VII" would mirror "Episode IV: A New Hope." Luke and Han would fill Obi-Wan Kenobi's role as reclusive mentors, and Ridley and Boyega would be much like Luke and Leia as young guns who need their help.
The source says the "find Luke" premise is based off the cast of young characters (Ridley, Boyega, others?) trying to deal with a problem they uncover that they feel they can overcome themselves, presumably something relating to the machinations of the Sith and/or Empire. They feel confident in their abilities to attack this challenge head-on and quickly realize they are severely out-matched and way out of their league. So they alter their plans and scramble to enlist the aid of Luke
As always, take this with a massive amount of salt!