Cant find realmlist.txt

[itdoesntwork]

Since i have windows vista 7, a problem happends when i download, my realmlist thats supposed to be named "realmlist.wtf" is named "realmlist.txt" but i cant find realmlist txt so that i can change it. Plz help me if you have had that problem before or if u just plainly know where it is.