This one's easy. If your original policy is lost and you do not just want a photocopy of the policy and need an original, just go to your title insurance agent and request a DUPLICATE copy of your policy. The agent may not know that they CAN issue a duplicate but if they contact their underwriter for instructions they can do it.
The typical procedure is for the agent to reprint the policy and type DUPLICATE ORIGINAL on the jacket.
This is normally not a request from a consumer with an owner policy. Photocopies of an owner policy are usually all a consumer would need. Lenders, however, may need an original policy in hand to meet secondary market standards for documentation.
In either case, it can be done. If for some reason the title agent is no longer in business or refuses to cooperate, then contact the title insurance underwriter directly. That would be the title company whose name is hopefully on the HUD-1 Settlement Statement, page 2, near the premium.