I also had this problem. I have an ipod nano 7th generation and a PC that runs Windows 10. I could sync my phone using itunes (I have an iPhone SE), but when I plugged in the ipod, the computer wanted to open it as a generic usb storage device (like a flash drive). After several hours of googling solutions, uninstalling and reinstalling itunes several times, and even trying to download the drivers from a questionable source and install them manually (the computer wouldn't recognize the drivers as belonging to the ipod when I tried it that way), I eventually was able to fix the problem by uninstalling itunes again and then reinstalling it by downloading it from Apple, not from the Microsoft store. Here's how I did that:
1) Uninstall your current version of itunes. (I'm sure most people know how to do this, but just in case: find it on the Start menu, right click on it, and select "uninstall".)
2) Go to https://www.apple.com/itunes/. When opening the link on a PC, it takes you to a page where the most prominent button says Get it from Microsoft, but do not click there. Instead, scroll down to where it says "Looking for other versions?" and click "Windows"
3) This will take you to a similar looking page, but instead of "Get it from Microsoft", it will say "Download iTunes for Windows now (64-bit)". Click there to download itunes and follow the instructions to set it up.
4) Once itunes installs, unplug the ipod if you haven't already, and plug it back in.
After doing that, my computer recognized my ipod and could also still recognize my phone. Hopefully it will be helpful for others as well.