What would we do if the lights went out?

[Kong Soo Do]

IS this thread about a day long blackout, a week long, or something that might be a forever situation? Are we talking a regional <say 100 square mile, 200, 1000 OR MORE).
Is there any hope for recovery or help by the government or is this a case of survival at all costs for the individual and families because there is no government and no communication possible ( heaven help those teens brought up with a cell phone attached to the end of their arm )
All of these factor have to be considered and I am seeing differing time lines being talked about side by side in this thread.
Lets set some guidelines on the time we are talking about

We can insert some general guidelines for the purposes of discussion. These are arbitrary and purely for purposes of establishing a frame of reference.

A 72-hour or less event. No doubt we've all been through something along these lines. Generally not that big a deal with a couple of caveats; first is if it is weather related. In colder climates being without power for 1-3 days can be a big deal if not properly prepared for ahead of time. Similarly, hot climates can be dangerous without power if not properly prepared, in both instances we need to be able to regulate core body temperature. Second caveat is that in some places it has been a big deal from a security standpoint i.e. looting, riots, arson and general mayhem.

And event lasting 4-10 days. Several considerations here; how intact is the infrastructure, how widespread is the event and is outside aid possible and forthcoming? The severity of the event will be determined to a large extend by the answers to those three questions. I will put forth the opinion that a person/family that has several weeks/months worth of food, available clean water, prior preparations with medications and general first aid will fare better than those that don't have that level of preparation. Particularly if the infrastructure is compromised to a level that food and clean water is not available beyond the three day mark. And again, climate can play a huge factor in this as well. If you are prepared and have no need to leave your home to find food/water/essentials then you won't necessarily find yourself in the midst of situations where your security is compromised (unless a security situation is brought to you in which case preparations for defense is prudent, and that isn't to suggest a millions rounds of ammo booby traps in the backyard, rather common sense preparations to protect self/family/community as appropriate to the situation).

11 days and beyond. As with above the caveats are the same and the level of severity will be determined by the questions posed above. However, though this 'category' is somewhat vague, the point is that the longer an event is lasting the more problems will arise. This would be the category of the OP i.e. an undetermined amount of time. If the grid was to go down...what was the cause? Possible scenarios are EMP (natural or man-made), cyber attack and physical attack. None of those are far fetched as each has happened already on a more limited scale but the possibility does exist for it to happen on a larger scale. Again, the large scale event is what the OP is discussing. Depending upon what collapsed the grid, the solution(s) may be available, difficult or impossible. How quickly could a cyber attack be fixed? If physical equipment is damaged or destroyed (much of which is no longer manufactured in the U.S.) how quickly could it be obtained and installed? If the grid were to go down on a large regional or national level the entire infrastructure is compromised, so how readily and realistically can repairs (if possible) be made while other scenarios play out? Logical questions.

We may never have another EMP produced from the sun or man-made. All the cyber attacks may just suddenly stop. There may be no further physical attacks on power stations. But what is the plausibility of each of those? What is the level of concern and/or prudence to prepare, as best as is reasonably possible in the event a grid-down scenario unfolds? That is the intent of the OP.