If your Xbox One's display is cut off, it could be due to a number of factors. Here are some troubleshooting tips to help you get back up and running:
1. Check your TV's input settings. Make sure that your TV is set to the correct input - often times, people accidentally leave their TVs on the wrong input setting, which can cause this issue.
2. Adjust your TV's overscan settings. Many TVs have an overscan setting that can cause this problem - try adjusting this setting and see if it fixes the issue.
3. Change your Xbox One's video output settings. Go into your Xbox One's Settings menu and change the video output settings to 720p or 1080p - sometimes, using a lower resolution can cause display issues like this one.
4. Power cycle both your Xbox One and TV. Sometimes, simply power cycling both devices can fix the problem - just turn off both devices, wait a few seconds, then turn them back on again and see if that does the trick.
5. Try using a different HDMI cable. If you're using an older HDMI cable, it might be causing signal issues that are resulting in a cut-off display - try connecting with a different HDMI cable (or even another type of cable altogether) and see if that makes a difference