Odyssey: Rear Entertainment System DVD Screen is Black, But Sound Still Works

We bought a pre-owned Odyssey last year. The rear entertainment system has worked without any glitches. However, while playing a DVD, the screen suddenly went black, and we can't get it back. DVDs still play, and the sound works just fine, but the screen is dead. If this is a major problem, we won't be able to afford to fix it, so I'm really hoping I can find some simple fix! Has any else had this happen? Any ideas? Thanks so much for any feedback!