How to open unknown locks of sony ericsson phones?

i have a SE k310i phone i have to open its phone lock code as i bought a used phone i dont know what the code is???

is there any way of opening tha unknown codes or locks ??????/

The default code is 0000.

If that does not work, try 1234.

^i have tried all of these but not working :(

My mem. card was once locked and I went to a mobile shop where da person used sum sftware or sumthing and opened the lock