Puchased app is not on my purchased list

You haven't changed countries since buying it, and is the app still in your country's store (developers occasionally remove their apps) ? If it is then is it hidden from the Purchased list : http://support.apple.com/kb/HT4919

If it's no longer in your store then do you have a copy of it on your computer's iTunes library or on your backup of your downloads/library so that you ca sync it back ?

You can't use a country's store unless you are in it. WIll you be returning to that country, and is that app still in its store ?