sudden change of my mac book air user name password

Hello Apple Communities,

I just recently brought an MBA 2012. But when I try to change may Laptop name, then I click to sleep my MBA, the password was change and I can't access it already. I don't know what happen but I never change my password. But I can't access my laptop using my own password. Can any one help me regarding this matter? I try to call Apple Support also but here in Dubai, UAE, I can't call in US because it was been block by the telecom itself. How selfish this people are. That's why if any one arround there who cann help me, can you please email me at jhnpdn@yahoo.com.

Thanks in advance for the kicd hearted person who's welling to help me.

John