I can’t use my screen recording app on my iPhone 11 it’s grayed out and not lit up how do I fix it

And you did a proper restart?

Is it doing this with certain Apps? For example it will be disabled for music or videos in the Music app. Others Apps may also restrict usage.

You might have some restrictions turned on for it as well . Look in Settings> Screen Time, and then tap Content & Privacy Restrictions. Apps will be greyed out if restricted.

You should also have your software up to date.

Try adding it into control Center

• In Settings > Control Center > Customize Controls, add Screen Recording.

• Or you can Restart your iOS device  (until the Apple logo appears)

If it was there, remove it, restart, then add it back