Conspiracy or reality? Who knows. I really don;t want to find out. Unless it's like some sort of worldwide zombie virus.... which, in that case, I'm tempted to say.... bring it on.
EMP is possible, I guess. It would take a suicidal nation to do it though. I'm guessing our military is well prepared to return fire from deep inside Cheyenne Mountain. Just how damaging it would be depends on a large number of factors. One is distance.... the further you are from the point of detonation, the less damage you would incur. It also depends on how "hardened" the computers and electronic devices are. If they are not running and at a distance, like cars, there might be no damage.
In a worst case scenario, where the enemy decides to hit hard and in multiple locations..... if successful, it would knock out the electrical grids in the USA. There are 3 interconnected grids. You could take out several major substations simultaneously and have the same effect without firing nuke missiles. A dozen coordinated strike teams could do it too. 3 to 4 attacks on substations in each of the 3 grids at approximately the same time, would start a cascading effect of shutting down the grids. Overloaded transformers will either blow or trip like dominoes falling, effectively taking the entire system of 3 grids down. The result would be grid down nation wide. It could be several weeks to months or even years before power gets back up depending on the method used to take it down and the damage caused in the process. Without electricity.... we are instantly in the 1800's again. We do not have the transformers needed to repair the grid setting in a warehouse since it would likely be thousands of them needed. They have to be built, one at a time, in a factory...which has no power to run the machinery needed.
Seriously in deep poo. Not many folks know how to live and survive in that kind of world. In 3 days, all the food in the supply line is gone. Gasoline isn't available either. 10 days in people are panicked and starting to eat things they would never think of eating. 30 days in, starvation starts to kill off the people unable to get food. At about this same time, lack of water for sanitation has lead to 3rd world diseases like cholera and dysentery making a return to this land. Lawless gangs will be roving looking for food, water, food, guns, ammunition, and anything else they want or need. They will kill to get it. Telephones, both land line and cell are not going to work. Calling 911 would be useless since the govt especially at the local levels and state as well as federal levels will be in a similar situation. So you can't count on the police to come to your aid. On the good side of that, the IRS will likely have lost all your records.
If the power is off for 12 months or more, some people familiar with this kind of scenario estimate that 90% of the population will be dead from one thing or another. Mostly disease or starvation. This of course does not factor in what any of the rest of the world would be doing during this time. If they are affected as well, because our govt was able to nuke them back.... they will have their own issues to deal with. However, if they are still operational, they will obviously become a player in the issues we are having to deal with as well as the problems directly caused by the grid down.
And it really wouldn't necessarily have to be terrorists with a plan or rogue nations with EMP's. Our sun is very capable of creating a first class Carrington Event all by itself. It did that back in the mid 1800's and all we had at the time were telegraphs. It set some of the telegraph stations on fire and melted the wires on the poles.... In fact, quite recently, there have been some sizable coronal mass ejections that missed our planet by mere days and had the potential to wreak havoc on our civilization. On those Carrington events, we do get a few days notice fortunately.
Should one of those events happen and we are "grid down" for more than a few days..... I would definitely miss being able to play music on the computer and to record.... but I probably wouldn't miss it too much. I'd be too busy fighting of the roving herds of zombies wanting to eat my brain and hunting for food on a daily basis.