Can't undo the parental lock (by 3 users)

Somehow my son put the parental lock on our TS2050J Jensen television. I am unable to get it off(ironic huh?) and cannot find our manual or find it listed on the Audiovox/Jensen website. I did try unplugging the television for 24 hours and then plugging it back in but we are still getting a blue screen with a lock and key symbol in the upper left hand corner of the screen.