Qual é o nome do arquivo para meus contatos no meu Optimus M correndo Froyo?
What is the filename for my contacts on my optimus M running froyo?
It's contacts.db but it's not a normal file or directory, it's a SQLite3 database in the following location which you'll need root to access:
Contacts are stored in a database. If you mean the filename of the app, it's probably Contacts.apk in /system/apps/.