Sony ericsson c905-deleted all my msgs.HELP

Hello,

hI ,

I have been experiencing a "corrupt" phone memeory full(even thought its not) message on my phone recently, i ignored it switched the phone on and off numerous times, this time when switching it back on, it appears to have erased all my messages inbox and sent, plus all my pictures and my contacts, i also can not send or receive messages when i click "creat" button it doesnt do anything.
Anything i can do to get this working or is it ready for mobiile heaven? i bought it second hand off ebay 3 months ago
Thanks
Chelle