how can i fix my memory of my R4 for ds? HELP?

once i was putting some games in my ds and then when i put it back in it said my memory was to full. i took off some games but still when i put it back it in it still said to full. so i took of all games and it still said the same thing. then i thourght it might be a syem problem mabey i took of something that was ment to be there. so i basically took every thing off and re format my R4 but still nothing happened i need HELP , HELP , HELP please