GT-S8300 forgotten phone lock code

Hello,
how do I hard reset my GT-S8300 ? I have forgotten my phone lock code so I cant even get to a point of dialing a phone number so *2767*3855# and *2767*2878# can not be used , will ony take an 8 digget code , have tried putting them in with no * or # and still no luck , Heeeelp please