well I have had this problem several times with different phones, the default lock code for this phone is 12345, if this does not work you can either
A:Try to hard reset the phone, if this does not work you will have to...
B:pay to reset your phone
To hard reset this model I believe you must enter *#7370# and when it reboots enter the default lock code of 12345, and if this fails well sorry I guess you'll have to pay=(
Good Luck man