Hi, i am a newbie here…I have a question. I do not know how did i change my region code. I remember i put 1 dvd inside my BenQ DW1620 inside, and play it with one dvd player called Hero DVD player. which dvd player doesnt change my region code automatically?
Welcome to cdfreaks 
The region free patched firmware is available from TDB’s site. You’ll find details in this sticky thread:
http://club.cdfreaks.com/showthread.php?t=114626
Or you can use a program like DVD Region-Free or AnyDVD.
oh… okie. Thanks. by the way , patching to free region , does it void the warranty of my drive?
if i patch it to free region, can i patch it back to original firmware?
Yes, and
Yes.