bit of help needed

[THE MAGGOT1]

sorry if this is in the wrong place,not realy sure where it go's. anyway,i have a dvd player on my pc, when i go into the select region select it says i have one change left before it locks,but when i goto change it from region one to region two it won't change it i goto plsy a region two disc but it says that it cannot play disc from this region.can someone tell mee how to unlock it or change i have tried several region killers but none work.