If this was very localised, people would get help, they may be temporarily relocated to another area that isn't affected. If it happened over a wide enough area there would be total meltdown.
This may not just be an academic question. I read an article recently about super solar flares. These happen every few centuries and would be enough to knock out electricity for weeks or months (by frying all the transistors). One happened in the 19th century (pre widespread electricity) that messed up telegraph systems. If it happened today over North America, it would have been total lights out for weeks over an area hundreds of miles across.