A standalone-home DVD player has a software installed which is also programmable to set the region...some models, and I am not sure if your one will do it (but give it a try) use following procedure:
Switch system on
open the drawer
press setup on the remote
highlight CUSTOMS SETTING
type 3333
press ENTER (or if not available select OK)
now you should see a "hidden" menu for the regional mode.
0 is normally the multi-region mode
press the required selection
press ENTER
press SETUP
close drawer and enjoy...
There is of course the chance that you may have to select a different code for the hidden menu, don't give up if it is not 3333, just try also the other possibilities like 2222 etc.