Let's say that giant solar flares or sunspots cause a worldwide collapse. All computers crash...civilization grinds to a halt. Is there something in place that would ensure civilizations rebuilding? There are many other scenarios that could result in civilizations downfall- natural and man-made. The question is- how long would we remain in a dark ages type of world? Are there repositories of knowledge that would survive for a long time and would we be able to easily unstand the instructions for say- digging a well? Planting crops?