One of my fast friend was cheated online or fraud was done to him?

Plz solve or give correct advice one of my friend was cheated over net 1 1/2 yrs ago .One person from nigeria had contacted him on his yahoo id & purchase some gold ornaments over net .He had send through speedpost but no money had come.After sometime he read somewhere abt them.Now that person is still contacting him.What he shall do or there any chances of money coming back?