Originally Posted by Zeruel

Contacts Blast is currently listed in the market. I'm not sure if being in Vietnam will preventing you from finding and downloading it. We have the download listed in all countries that presently support paid apps. It is possible that it is not available in Vietnam right now.

The best way to find it is to load the market app then click the Menu button on the main screen. Then click search and type in: contacts blast

This should bring up two results (Contacts Blast and Ringo Lite [for some reason]).

If you can't find Contacts Blast it may be a problem with the google marketplace. You can also try restarting your phone to see if that helps.