27-year-old Marcus Smith was last seen in Preston on 1 February.
Concern is growing for Marcus, 6ft tall, of skinny build with long brown curly hair.
He was last seen wearing camouflage trousers and camouflage jacket and uses a wooden staff to aid him walking.
Marcus has links to Kendal, York, London and Blackburn.
PC Oliver Bayliff said: “If you’ve seen him or know where he may be, please don’t approach him but contact police instead.”
“Marcus – If you’re reading this appeal, please get in touch and let us know you’re safe.”
Anyone with any information on the whereabouts of Marcus should call 01254 353901 or 101 quoting log number 983 of 6th February.