Minod Monger, aged 23, disappeared from his home in the Ecclesfield area of Sheffield on Monday, June 19.
Today, two weeks on, Minod is still missing, with just one confirmed sighting of him on a CCTV camera in Parson Cross around an hour after he left home.
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Urging people to help find his brother, Prem Monger said: “Minod we need to know you are safe.
“You are not in trouble with us, your family or the police.
“If you are in Sheffield, please look out for my brother.”
Minod, originally from Nepal, was wearing a white jacket with a fur hood, grey tracksuit bottoms and black croc shoes when he vanished.
He has additional learning needs which mean he can become very stressed around people he does not know.
Anyone who spots him should call 999.
To pass on other information which may help officers searching for Minod, call South Yorkshire Police on 101 and quote incident 715 of June 10.