You say you started in 2011 so obviously it was easy to mine back then, however how long did you leave it running give an estimate, 1 day 1 week a year ..... ??
Do you know the PC's specs because if it was a rubbish computer then you may have so little coins its not worth worrying about
I don't think hes coming back:
Date Registered: January 05, 2016, 09:35:16 PM
Last Active: January 05, 2016, 11:19:53 PM
I don't think there is much we can do in all honesty. He needs to know if he stored it online or on PC, if he cant say that there is nothing we can do. If online I would have him check email from then... but chances of it being there from 2011 till no is slim.
But I think this is a moot point as I do not think hes coming back looking at profile was only online for around 2 hours.