1st generation IPOD

In order of ease:

1. 1. from your iTunes library (which I'll take a guess, you no longer have access to)
   2. a backup of the hard drive from your computer
   3. use a computer repair company to read a drive on a broken computer, or buy an external hard drive bay and put the hard drive into it and read that (in both cases, that is if the drive itself can be accessed and is still working)
   4. third-party tool to recover the data from the iPod itself

There is no simple method to copy music on an iPod back onto a computer (iTunes has never had that ability). Instead, see this tip from fellow user tt2: Recover your iTunes library from your iPo… - Apple Community

He explains what has to be done and lists several programmes that can recover your music. He covers the point I made in 3, that may be possible to use a purchased hard drive bay and read the drive that way. Later in the article he lists third-party software. Some of that software offers limited free copying, some requires a payment to begin with. Possibly the easiest one to use is Media Monkey which is free.