I think you still do not grasp the scope of this problem. Where are these books? Remember, there is no internet, no phones, no long-distance travel and only sporadic regions with electricity. All information is now regional and very limited. All of the existing SC fabrication equipment is built upon the knowledge and experience of previous generations of engineers and scientists. I have little doubt that other vital 21st-century industries are in a similar situation.Any people doing the "relearning" would make far quicker progress by reading existing books and computer records, and restoring existing tooling, than it took mankind to learn everything the first time around.
You would have to start over, most likely without oil, since all of the easy oil has been extracted and consumed over the past two centuries.