Did you drop it? that might have messed with the electronics or shifted the battery?
Did you just start your Tamagotchi?
Did you accidently or purposely hit the reset button? In that case you should be able to just download but (other than when I first started my tama) I haven't hit the reset button.
[SIZE=14pt] Does it need a new battery? Did you drop it on the ground? Did it get wet? Did it get crushed? You need to think what you did with it in case you broke it.[/SIZE]