Put the following into indirect speech:“I meant to plug in the electric blanket but I plugged in the electric kettle

При переводе утвердительных предложений из прямой речи в косвенную мы изменяем времена глаголов в придаточном предложении согласно правилам согласования времен, поэтому: 

She told her guest that she had meant to plug in the electric blanket but she had plugged in the electric kettle by mistake and she was always doing silly things like that.