Well, you must have some paperwork to prove that you were issued a visa. If you think your passport is really lost and you wont be able to find it, report it as lost, get a new one, and contact CIC to issue you a new visa. (They might need to see the proof that you've reported your old passport as 'lost' to authorities before they stamp visa on your new passport). Good luck.
Thanks Adnan,
Does it have to be same High Commission/Consulate or I can apply to any Canadian Embassy?
Thank you