how do I export songs from Itunes to a folder on my PC?

Perhaps you were actually dragging from the folder where the songs are stored (using Windows Explorer) to the external drive. If all you wish to do is copy the songs (or albums), then you don't need to use iTunes to do it.

Don't forget, the music listed in your iTunes Library is not in iTunes. Instead, iTunes knows where the file for each song is located on your computer. So bypass iTunes and simply use Windows Explorer to copy the files to the external drive.

I've just checked and I can drag and drop from iTunes to say a folder on my desktop with iTunes 12.13.1.3. iTunes may not want to export to flash drives for reasons. If so you can make a local copy first, then cut and paste that to the final destination, or you can try my ExportToFolder script which should give you control over the layout of the exported files.

tt2

It's still easy to locate artists in iTunes, look in your Library under Artists. If you don't see the artist you want, use iTunes' Search bar, which is in the top right corner of the iTunes window:

The drop-down arrow next to the magnifying glass allows you to filter by Artist, or All. You may need to make sure that it is on one of those two options.

However, that's in iTunes. To find the artists in Windows Explorer, so that you can copy from there to your external folder, use Windows Explorer's search bar:

You may notice that this particular artist does not have its own folder, whereas most artists do. This is because an artist folder is created when you have an album by that artist. In this case, I don't; all these songs appear on compilation albums.