Try the following troubleshooting steps:

1. Check the digital aerial cable connection from your television to the wall socket. Make sure they're all secure. If you're connecting wirelessly, try switching the router on and off again.

2. Try a channel scan. Press the Menu button on your television remote and select Set up, Installation, Channel Search, Channel Scan, Scan Now, or something similar. This should reload all the available channels in your area.

3. Check that the tuner is correct. You can find this information under the Set up, Installation, Channel Settings, or something similar. Here, you can select which type of signal you're using (e.g. digital terrestrial or cable).

4. Try resetting the Factory Settings (which can also be found under Set up, Installation, Factory Settings, or something similar). However, bear in mind that this will erase any personalized settings you've made.