Check the App Store for Musi and reinstall it if it is available
Sign in with the same Apple ID you used before
Open the App Store and tap your profile icon
Tap Purchased
Search for Musi in your purchase history
Tap the download icon if it appears
Check whether the app is hidden in your purchase history
Unhide it in your account settings if needed
Update your iPhone to the latest iOS version
Restart your iPhone
Check your internet connection
If Musi is no longer available in the App Store, use an alternative music app
Contact Musi support for account or app availability help
Restore your iPhone from an iCloud or iTunes backup if the app was previously installed and backed up