Good afternoon dianne3143,
Welcome to the Apple Support Communities!
If I understand your question, your iTunes library on your Windows PC shows all of the purchases you've made in iTunes through the years. You updated your iPhone 11 to iOS 13.4.1 last night, and the purchases are no longer showing on your iPhone. Is that correct?
If you have not already done so, before we begin troubleshooting, I would suggest making a backup of your iTunes library to an external drive.
Back up and restore your iTunes library on your PC
First try restarting your iPhone and your computer to refresh them and the connection to the internet after doing an update.
What version of Windows is running on your PC?
Make sure you have the most recent version of iTunes running on it:
Update to the latest version of iTunes
Do you have a subscription to Apple Music on your iPhone and Windows PC?
If yes, check to see that the subscription is still active, then follow the instructions below to sync the iCloud Music Library.
See or cancel your subscriptions
Use iCloud Music Library on PC - iTunes User Guide - iTunes 12.10 Windows
If you do not have a subscription to Apple Music, follow the steps below to sync your iTunes library on your PC to your iPhone using the Lightning to USB cable. Personally, I find it easier to create playlists of the music I want on the computer, and then sync just the playlists to the iPhone.
Create a playlist in iTunes on PC - iTunes User Guide - iTunes 12.10 for Windows
Use iTunes to sync your iPhone, iPad, or iPod with your computer
If you just want to redownload your purchased music to your iPhone, follow these steps:
Redownload apps, music, movies, TV shows, and books
See your purchase history for the App Store or iTunes Store
Please reply to this thread if you can't get the purchased content that you see in iTunes for Windows on your PC synced to your iPhone 11.
Take care.