Sun Valley Police are baffled by the mysterious disappearance of a 21-year-old man. Police Chief Cam Daggett says Dex Gannon was visiting an old high school friend who lives in the Morningstar neighborhood of Elkhorn on Dec. 30.  When the friend went to check on him the next morning, Gannon was gone. The pair had planned to go skiing that Friday. Gannon is believed to have left the residence on foot wearing a new yellow snowboard coat with teal accents.   He is about six-feet tall and weighs around 170 pounds.  Family members told police that Gannon was distressed at the time of his disappearance.  He left his cell phone and wallet at the home. Police searched the immediate area around the home Friday. Daggett says no foul play is suspected in Gannon's disappearance. Meanwhile police hope to look through Dex Gannon's electronic accounts like e-mail and Facebook for any activity that could give them clues. Chief  Daggett says they are working on getting access to his accounts.  Police say Gannon was unemployed and had enrolled in classes that begin later this month at  Boise State.