You really shouldn't change the region code more than once to fit your particular area. But if you want to try to change it that last time, you can use ImgBurn for this. ImgBurn is a free burning program found here: www.imgburn.com
Install ImgBurn. Start the program. Click on any of the choices...Discovery would be fine. Now, at the top of the main window in ImgBurn, click on Tools-->Drive-->Regional Code-->Change.
I think it is still possible to flash your drive using region free firmware. Then you use software for playback of dvd-video that doesn't check region codes. VLC media player can do this, and is free to download and use. www.videolan.org
So, make sure you have the right model number...and look on this page for the appropriate firmware for your drive: http://tdb.rpc1.org/
I'd use the 1.41 version for your DVR-110. There were two similar models, the 110 and the 110D.