Is there anything I can do if I just said guilty to get out of jail?

I was charged with grand larceny. My new found friend took me to his place because I had no place to go; I spent the night and in the morning he asked if I could pawn his guitar amp because he had no ID so I did. Couple days went by and the cops were looking for me. I went to the jail house because I couldn't get a hold of the detective to tell him what happened, but instead got arrested never got a phone call or anything didn't get to see my court appointed attorney until I was in front of the judge a month and a half later. She handed me a paper where all my rights had been checked off and waived and she had circled guilty. I told her I was innocent and she said would you like to be innocent and stay in jail for a year or be guilty and get out today. Other than this, my record was completely clean and I had never been in trouble with the law.