asus A6J

ive recently perchased a asus A6J notebook off ebay. on start-up at the american megatrends screen it says hard drive locked, enter password:. i can’t get in contact with the seller as they wont return emails that i have sent them. asus asured me that the notebook was not stolen as i rang and checked with them before bidding. asus also tell me that there is a master reset which will over ride this password, but inorder for them to do that i need the original purchase receipt from the last owner, who i cant contact. does anybody have any idea how to clear this password??? mind u its not a bios password.