I purchased the Panasonic DMR-EZ28K & everything was fine...until I tried to watch a DVD from overseas(3 ). the disc couldn't be recognised because of the region code. How to change the code to free?

Buy a UEI remote (one-for-all, radio shack, etc.) and enter THESE (http://www.avsforum.com/avs-vb/showthread.php?p=15647114#post15647114)codes. There are more detailed instructions out there if you search, but I don't remember where.