> How long would it take for the world to come back from that without access to our current electronic tools and online repo of limitless knowledge?
In the initial post-collapse scenario there'd be a massive die-off. Cities would be impossible to live in, only those with access to water supplies and crop packages would get to live. Those in the third world would, ironically, be much better placed than those in developed countries from the perspective of not noticing things going sideways.
The common theme, regression to more local form of government, i.e. feudalism, would probably play out.
To build back up from there would take hundreds of years. You'd have to be in a position to re-establish supply chains. Which would require both the ability to organise on a significant level and the ability to have a crop surplus to support non farming specialists.
The saving grace would be the existence of certain select bits of knowledge; the idea of levers, basic mathematics entrenched in a very efficient number system, simple bits of tech like heliographs and one time pads, the printing press. Stuff that, if you're aware it's possible, you can make with relatively little effort. And social themes, like the idea of loans and relatively free trade that allow innovation to happen, the scientific methods - stuff like that.
I don't think that having books about how to make a machine shop would honestly make that much difference. We could work that stuff out for ourselves by the time we were in a position to operationalise it.
Hundreds of years, most of which would be things like getting agriculture in place, waiting for the population to grow to a decent size - things like that - rather than reinventing stuff.