How do you get the Season 2014 - Solo Silver?
It was a ranked reward. Riot's description in the client reads: “Earned by achieving Silver in the 2014 ranked season in Solo/Duo.”
Is the Season 2014 - Solo Silver still available?
No. The Season 2014 - Solo Silver was a ranked reward. To earn it, you had to reach Silver in Solo/Duo during Season 4 (2014). Riot does not hand out past ranked rewards again, so you cannot earn this icon anymore.
