The `Terminator 3: Rise of the Machines` star disappeared in June after checking out of a Los Angeles rehabilitation clinic against doctors` orders but he has now contacted his wife Rose Murphy Stahl and other family members.
According to TMZ.com, Nick is "in a good place" and is attending Alcoholics Anonymous (AA) meetings.
The 32-year-old actor has not yet moved back home with Rose - with whom he has a two-year-old daughter Marlo - but is instead staying elsewhere.
After leaving the treatment facility several weeks ago, Nick - who has a history of drug and alcohol abuse - was reported missing by his friends and family after he failed to return to a pal`s home.
After reporting him missing to the authorities, actress Rose refused to continue to look for him, insisting her priority was there daughter.
She said: "I`m backing off. He knows exactly where home is. It`s the loving thing to do for him, myself and our daughter."
Nick has disappeared on two occasions this year. In May, he went missing for over a week and when he re-emerged he was admitted to a rehabilitation clinic.
The troubled star had been living apart from Rose and Marlo since February.