I am a new Blackberry user and I seem to have changed something that has messed up the find function in my address book. Now when I try to find a contact in my address book by inputing a letter I am told that there are no addresses. There are in fact hundreds in the address book and it is possible to scroll through them. The only exception is one that I added this morning which it does find. I have been through everything I can think off to restore this function but to no avail. Can anyone help.

Details are:
Blackberry 8820 v 4.2.2.168