How do I recover my iTunes library after Windows reinstall?

I have both an iPhone and an old iPod Touch (that I use as a music source in my car), and both are set up with an extensive playlist of music that I have accumulated over many years. I maintained that library using my Windows 11 computer, periodically adding to the library and synching and backing up both my phone and my iPod. Recently, I had a problem with my computer for which the solution was to do a full reinstallation of Windows. And of course that also meant reinstalling all my software. So now I am faced with the problem that I no longer have a copy of my iTunes library on my computer. So how should I proceed with my phone and iPod? From what I've read, synching a device with a computer with an empty iTunes library can result cause the iTunes library of the device to be replaced by the empty library - and that is something I definitely don't want to do. I suppose one option would be to accept that the existing iTunes library on my devices is frozen at its current state, but I would really prefer to continue to be able to augment it over time. So what are my options?

[Re-Titled by Moderator]