I am having trouble signing into iTunes

I am having trouble signing into iTunes I have attempted to sign into iTunes multiple times. Each time I enter my password it informs me that no one has use the user ID or the Apple ID and it will not let me sign in. I’m able to sign into the iCloud with the same Apple ID I am using for iTunes. I simply do not know what to do and I cannot locate anyOf my downloads in the app library or on the home screen. Please help