gave black screen after putting 120 hz

Hi KelwinLaurindo1, I hope you're doing great out there despite the issue that you're experiencing. I am an Independent advisor and I am here to help you in regards to your concern.

It means that your TV does not support it. To reset it simply follow the steps below:

1. If there's a disc in the Xbox console, eject it.

2. On the console, press and hold the Xbox button for 10 seconds to turn off the console.

3. Press and hold the Xbox button and the Eject button until you hear a beep to turn on the console. You’ll hear one beep right away and a second beep 10 seconds later. The power light will flash on before the second beep. Don’t let go until the second beep occurs.

4. In either case, this will boot your console in low-resolution mode (640 × 480). To reset this setting, press the Xbox button to open the guide. Go to Profile & system > Settings > General > TV & display options, and then select the resolution you want from the Display dropdown.

the normal that goes from console to television.I'm from Brazil, I don't know if anything changes

what type of HDMI cord are you using?

does not support 120 hz supports 60, the television is by Panasonic

You're very welcome. Please stay healthy and safe!