Hw to get back my contacts?

Hi!
I hv Nokia 5320 Xpress-music mobile phone I hv lost my all contacts.They are in the phone but mobile is not showing them into phone book, neither it is allowing to save new contacts nor itis saving from the backup created in memory card.
It is copying from memory card but not showing the contacts in phone book.
I had updated its software but the problem remains same.
Plz help me how to get it back?