Mystery surrounds the disappearance of Melbourne man Tej Chitnis, who hasn't been seen or heard from in more than two months.

The 21-year-old was last seen by his family leaving his Burwood East home on April 27.

Despite having plans to meet them for dinner, he never arrived.

CCTV footage and mobile phone tower information places him in Healesville later that same day - in what police describe as the last official sighting of the young man.

Both his family and police believe he's alive despite not accessing his bank accounts or using his mobile phone since April 27.

His mum, Reva, believes Tej is taking some time out after it was revealed to her by police that he had not been attending university for the past two years.

That news was a shock at first, but then gave the family a sense of hope and an understanding of why he had left.

Mrs Chitnis, husband Jayant and eldest son Rudra now spend their weekends travelling across the state in search for Tej.

"We keep going to the spot where he his car was last seen in Healesville ... we've looked for him at Phillip Island. We need to do something. We can't sit at home any longer," she told AAP.

Police say they are still treating his disappearance as a missing persons case.

They have investigated many possible sightings, most recently at Berwick Train Station and a McDonald's in the city.

But they have yet to provide a strong lead.

Acting Detective Senior Sergeant Graeme Savage says Tej's car, which still hasn't been found, is an important piece of the puzzle.

They are calling on anyone who has seen the VW Golf with the registration number TTF 517 to contact police.