try the ff:
1.check your phonebook for possible duplicate numbers entered to it. you can best viewed and verified phonebook using pc suite installed in your computer.
2. try to use this format(mobile country code+operatorcode+mobile#) when saving numbers in your phonebook sample +63917xxxxxxx, x= your mobile number.

reinstalling OS the last resort as this will set your phone OS to its factory settings..all data will be lost unless u made a back up.

good luck

I try that before..the funny thing is the first message people sent to me,it showed their name..but their second message my phone showed me their numbers instead of names..

I think of reinstalling OS as i got this problem when i updated my software in the phone..but i dont even has the slightest idea how to do it..

it's obvious !! try to dial that name's number !! and make a call !! wut it'll show ? if a name > then the phone needs new software , but if it's a number > then u added that number in two different places

When i dial the number..their name come out~Then how now??