This is a situation that a lot of us don’t think about. We all got so much used to a high-quality lifestyle that we take things like electricity and water at our homes for granted, or at least we underestimate the effect of their absence. This is not an imaginary situation, this is something that could happen after a storm or hurricane.
Here is a good article about what should be done in a situation where you are living without electricity for 3 full days. The main issues covered are medication and first aid, water, food and cooking, lighting and keeping warm.