In the scenario you described, where the victim is unresponsive and not breathing normally, you should begin chest compressions immediately. The correct course of action is to:
Begin chest compressions at a rate of 100-120 per minute and give 2 rescue breaths after every 30 compressions.
This approach aligns with the guidelines provided by organizations such as the American Heart Association for performing CPR on an adult in cardiac arrest. The chest compressions help maintain blood circulation, and the rescue breaths provide oxygen to the victim. Remember to continue this cycle of compressions and breaths until emergency services arrive or the victim begins to show signs of life.