It doesn't work when I press a key

Hi have a Casio WK-220 electronic keyboard. I was using it one day and when I pressed a key it just turned off complicity. I thought the battery died so I got some fresh batteries and the something happened again. So i tried the ac adapter but it still unplayable. So I don't know if it's the keys problem or not. I am hoping if you guys have a way to fix this. Email me back at lieovellian@yahoo.com