OMG PLEASE HELP!!!!?

OKAY! HELP! I put a game on my PSP right? i downloaded.... but it didnt work so i took it off.. BUT the memory cards still LOW when before i put the game on there it was 600 on the memory card but now its 180!!! but i deleted the game WHAT IS THE PROBLEM? im not good with electronics... ;-; and muy computers a UBUNTU if that has to do with anything....? i searched in all the PSP's folders, couldnt find the game caus i deleted it but its still saying my memory cards low wtf happened?