The Terminator 3: Rise Of The Machines star first disappeared for more than a week last month (May12) but he re-emerged and was admitted to a rehabilitation clinic.
Stahl, who has battled a drug problem, walked out of the California centre earlier this month (09-10Jun12) and went to stay at a pal's house.
However, his family and friends are once again searching for Stahl after he failed to return to his friend's home. He was last spotted on Thursday (14Jun12).
A source tells EOnline.com, "Now he's disappeared. We can't find him anywhere. He has not made contact with anyone. We are all just desperately looking for him.
"Everyone just wants him to come home. It's a terrible situation. We are searching, but we've had no solid leads."