I have a Sony Ericsson. i have a Sony Ericsson w300i and when i turn it on it says phone lock

Question

i have a Sony Ericsson w300i and when i turn it on it says phone lock code, and its not the factory one i dont think and i dont know it to unlock it . I've tried a couple but they didnt work and you cant press the star or the pound key as part of one they dont work, can you help me pleasr?