Problems with my TI 83 plus calculator! help!!!?

my calculator is not behaving right now. im trying to do my hw an di just turned it on and i typed in a couple numbers and say i typed in all 8's , all of the eights were missing pieces of the number!!! and then when i press clear or delete, theres underlined parts (like the ones in hangman) all across the screen!! i went onto the TI website but they had nothing for this problem. basically, wen i turn on my screen and i type in some numbers, its looks like somebody ate parts of the numbers, it looks like theres crumbs on the screen! i even changed the batteries (only the AAA ones,). wat should i do?? i really need this for school.