How can you make your electric piano sound louder?!!?

its a casio celviano and a few years old now but the slide control for the volume has stopped working - its getting worse and worse so you can hardly hear yourself playing as you have to have it at a certain place just to get any sound. just wondering if i can buy an amp or something and make it louder?! i really dont have a clue but its hopeless the way it is and im not exactly an electrician!! thanks all.xx