The asker claimed to have found a cockroach in a can of Pepsi. They kept the roach.
Proof will be the issue, so it is good you kept the cockroach. Hire a personal injury attorney. Make sure it is a good one who can deal with a contaminated food issue. The attorney will look at your case and help you determine if it is appropriate to go forward. The consultation for this should be free. Such attorneys work on a contingency fee basis in the United States, so if s/he decides to take on your case there should be no cost to you unless the attorney gets compensation for you. This of course assumes you are in the United States.