Getting support on Windows PC instead of Apple product

Not necessarily, it depends where the music came from originally.

If you purchased all your music from the iTunes Store, then yes, it should all be available in each of your iTunes Libraries - providing you have signed into your iTunes account in each Library with the same ID as you used to buy the music originally, and have made efforts to download anything that is not already in that Library. This is subject to a maximum number of libraries, you can't just keep adding more.

But, if any of your music came from other sources, such as Amazon, Bandcamp etc., that will only show up in your iTunes Library if you download it to that specific computer. To get that music onto your second computer, you need to download it from the account that you hold with that store or source to the second computer.

If you're looking for help with iTunes on a Windows PC, then ask here. What exactly is the problem?