The man's family recognized him in a Youtube video that showed him singing a popular Bollywood song for money on a Mumbai street. The 66-year-old man, a former soldier, went missing in 1978.
They had heard nothing of their missing relative for 40 years, until the family chanced upon a viral Youtube video a few days ago.
The video showed a grey-bearded man singing a Bollywood classic for money on a street in Mumbai.
The family recognized him as their missing relative — Khomdram Gambhir Singh, who went missing aged 26 in 1978 from his home in the remote northeastern state of Manipur.
"I could not believe my eyes when one of my nephews showed me the video footage. We had lost all hope of seeing him alive again," India's The Hindu newspaper quoted Gambhir's brother, Khomdram Kulachandra, as saying.
Kulachandra and others informed the local police, who spoke to their counterparts in Mumbai, 3,300 kilometers (2,000 miles) away, where Gambhir was living rough.
"He was making money as a beggar signing old Hindi songs," said Firoze Shakir, who shot the video and uploaded it to YouTube in October last year.
'Ray of hope'
In the video, Gambhir can be heard telling Shakir that he quit his job as a soldier to take over his family's farming business from his aging father.
He soon quit farming and came to Mumbai where he worked as a daily wage laborer for a bit. He eventually took to begging after suffering a couple of accidents, Gambhir told Shakir.
There is no clarity as to why Gambhir left his home. Local reports said he had gone into a depression after separating from his wife following a brief marriage shortly before going missing.
Mumbai police found Gambhir outside a railway station. He was flown back to live in Manipur on Thursday.
"This story is a ray of hope. If a video can change a man's life there can be no bigger miracle than this," said Shakir.