I bought a game and it wants me to buy it again

maybe its a Xbox live gold game

Hello

As mentioned anything you own will appear as owned in the Xbox store or be visible in your purchase history. Having clips of games doesn't mean you own it. That just proves you played it. It sounds like it may be linked to another account or you might have
had the disc version.

I bought call of duty modern warfare almost as soon as it came out and now it wants me to buy it again

its been too long so its not in my recent purchases, its still downloaded onto my account i just cant play it still. I can prove that i have it because i have many clips if playing the game and i also can see that its downloaded on to my xbox. I dont want
to pay for it again of course

Sometimes the Xbox system tells you that the game is not yours even if it was previously purchased.
To validate that the game is indeed shared in your account, go to the Microsoft store and search for the game.
in the purchase options it should appear as "install" if the option you give is "buy" the game is not registered in your account purchases.
check if you bought it with a secondary account on your console and download it with that account.

I would contact Xbox support. They can look through your entire purchase history and tell you exactly what happened.

You need to contact main Xbox support, as no one here can look at your account details.

https://beta.support.xbox.com/contact-us