Final answer:
If you are alone and did not witness the sudden collapse of an infant or child, assess the situation, ensure their safety, and call emergency services.
Step-by-step explanation:
If you are alone and did not witness the sudden collapse of an infant or child, the first step is to assess the situation and ensure the child's safety. Check for any signs of life, such as breathing or movement. If the child is unresponsive, call emergency services immediately and follow their instructions.
*Do not leave the child alone and unattended.
*Do not attempt first aid if you are not trained or confident in your abilities.
*Do not move the child unless instructed to do so by emergency services.