I've had a similar problem, but I didn't lose ELO for it. There's recently been a bug, where you dont even get into the champ selection, even though you're actually in. My friend got in a ranked game w/o me. So I just restarted my client (checked my ELO first to see if I would lose any), and nothing happened. No penalty, no ELO loss. Has happened to my friends quite alot too.