Need help from someone who knows how to play well.

I can't play anyone else BUT Shaco jg. That is it. If I try to play anyone else I suck. Like.. 1-7... 1-4....0-18 even. Of course every 1/4 games I have a 5-4, 4-4 sure. But I want to elo up in Ranked and am currently sitting at Bronze 1 permanently. If I don't get my Shaco in a ranked game, there is no hope of me winning. At all. I was wondering to see if any players who know the game well enough that could give me tips and advice on why I can't play anyone else but him? I even try playing the characters like Ashe and such that I have been playing for a LONG time, and cannot do it. Just Shaco. If anyone could help me out it would make a player who can only play 1 game a day maybe very happy. Thank you!