The lancer

Well depending on how far you are in the chapter.....you can get it back. When you find the Acid things shooting out acid...go to the right and shoot the thing shooting acid and run. There is a lancer there.

You can pick up any lancer you find along the way.
At the part where those things that shoot acid, don't go left, go right, the dead COG here has a lancer you can pick up.

I think you can take carmine's lancer too,

There is a couple in that level layin around .. I made the mistake and threw mine away too but they are along the path tht your on

Well, you can find a locust that is carrying around a Lancer. You will know that he has one because he will shoot at you. <:

Kill him, and then pick up his Lancer.

The locusts do sometimes carry around lancers, listen for the sound of a lancer firing and look for the constant stream of bullets. Oh, and for gods sake don't get close to them to try to melee, you will find yourself in pieces.

When you complete a chapter, you can get it automatically back. Usually there randomly placed on maps so you don't actually lose it, just make sure when you pick up a weapon your doing it on the secondary weapon and not on your primary weapon the lancer.