Connor Hegarty was last seen at around 2.30am on Monday, driving a silver Vauxhall Astra in Tulketh Brow. His car was later reportedly in a crash near Railway Bridge in Fylde Road, and close to Ashton Basin, police said.
Searches of the Lancaster Canal, near to Ashton Basin in Preston were carried out but nothing was found a police spokesman has confirmed.
His family are now desperately appealing to the public for help in finding the missing man.
Connor's cousin Karen Jackson said: "[He] has been missing from the Preston area for days now and his family are worried sick, if anyone has seen him or knows where he may be could you please contact the police or myself.
"I will pass messages on to his mum, she's desperate to know if he's safe."
Officers have said that they remain 'very optimistic' about finding Connor, who was wearing a white t-shirt and black jeans, safe and well.
Earlier this week, PC Amy Cooney, of Preston Police, said in a statement: "Connor has been missing for several days now and we are concerned for his welfare.
“If you have seen him, or know where he is, please contact police.
“Furthermore, I would urge Connor, if he sees this appeal, to contact us to let officers know he is safe and well.”
Anyone with information can contact police on 101, quoting log reference 0530 of August 6.