It would be helpful if you could provide more information.
What version Tamagotchi toy do you have? (V3, V4, V5, MusicStar, ... ?)
What is on the screen? (Nothing, a flying saucer, something else, ...?) A picture would be helpful.
What do you mean "my actions still work"? You can see the stats, you can play the built-in games, you can get a login password for TamaTown / TamaExpo / MusicCity, you can feed meals & snacks ...?
I think tamagurl656 means that there is a line across the screen. That happened to me on my Music Star. I just downloaded it and all was well. Just try downloading it, Tamagurl656.