Memory problem in Nokia N73

Hi,
my Nokia N73 mobile has about 43 MB of internal storage.I dint put any heavy music or anything in that because i store everything in an memory card except messages and contacts in my phone memory as default.The problem is my phone memory is magically full and if i search in,i don't get any thing to delete except that messages and contacts(these are in Kb),so literally i don't know what to do except formatting the phone memory,from this problem i cannot message to any1 because the phone is not letting me to do so and also annoying free-up memory message from phone...please help me if there is any software to fix this or anything else...thank you