what is this

You modded your game. Don't whine to Mojang about your wrongdoing.

thanks, how did you know

how do you delete mods!!!! please help

Please do not report issues for modded clients. If the issue persists in vanilla minecraft, then feel free to post a new issue ticket. Remove mods by forcing an update in minecraft.

I saw this:
Is Modded: Very likely; Jar signature invalidated.

To delete mods, clear your bin folder. The client will make a new bin.