The 23 year-old, from Livingston, was last seen at his family home in Poplar Grove around 6pm on Saturday, February 13.
The keen musician has not been in touch with anyone since.
In an emotional appeal at Livingston Police Station this afternoon, his family said their fears were growing, and they just want to know Matthew is safe.
His dad, Ian Elmer, said: “It’s been a living nightmare, time has just stopped still for us.
“We just want Matthew to know that he’s not in any trouble - not with us, not with the police.
“All we need to know is that he is safe.”