Michael Patrick Martin, 25, from Salford was last seen at address on Sidmouth Drive, Blackley, in the early hours of Sunday 7 August 2016.
His car has since been found on Vermere Avenue, Blackley.
Detective Inspector Clare Devlin, of Salford Borough said: “This disappearance is very out of character for Michael, and we are worried that he has come to harm.
“We believe he may have been the victim of an assault, and if that is the case it is even more important that we find him soon.
“If anyone has seen Michael in the last few days or think they know the whereabouts of him, please contact police immediately.
“Michael, if you are reading this message, your father would like you to call him so he can be sure you are ok.”
Anyone with information of Michael’s whereabouts is asked to call police on 101 or the independent charity Crimestoppers, anonymously, on 0800 555 111.
