Try following these steps first
- If you have a Siri Remote or Apple TV Remote, charge it for 30 minutes using a Lightning to USB cable and a USB wall charger. If you have an Apple Remote, replace the battery.
- Unplug your Apple TV from its power source. Wait at least 6 seconds, then plug it back in.
If your remote still isn't working as expected, follow the steps for your type of remote. After each step, see if you still need help.
Siri Remote or Apple TV Remote
- Press and hold the TV/Control Centre button
and the Volume Down button 
at the same time. Hold the buttons down for about 5 seconds, or until the status light on Apple TV turns off then turns on again.
- Release the buttons, then wait 5–10 seconds. A Connection Lost notification will appear on your TV screen.
- After your remote has restarted, a Connected notification will appear on your TV screen.
If your remote still isn't working as expected, try following these steps:
- Point your remote at your Apple TV. Make sure that the remote is about 8cm from the Apple TV.
- Press and hold Back
(or Menu) and Volume Up 
for 5 seconds. - If asked to do so, place your remote on top of your Apple TV to finish pairing.
If you can't pair your Siri Remote (2nd generation) or Apple TV Remote (2nd generation), make sure that your Apple TV is updated to tvOS 14.5 or later. You can use the Apple TV Remote on your iPhone, iPad or iPod touch to navigate your Apple TV to check which version of tvOS you have.
If you still need help, contact Apple Support.
Apple Remote (aluminium or white)
- Unlink your Apple Remote from your Apple TV. On your Apple Remote, hold down Menu and the Left arrow for 6 seconds. Then on your Apple TV, look for Unlink
above an icon of a remote. - Link your Apple Remote to your Apple TV. On your Apple Remote, hold down Menu and Right for 6 seconds. Then on your Apple TV, look for Link
above an icon of a remote.
If you still need help, contact Apple Support.