Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
There have been several known issues with this particular model having the internal freeview tuner fail. Though yours is only 5 years old, it is an 8 year old model (released in 2006), so the technology predates some of the digital broadcast standards used today, and it may lose compatibility with some channels over time.
There are a few things to check here,
first, disconnect power to the panasonic, at the mains, for 60+ seconds to reboot the system
it will take a few minutes to start back up. If no change, go into the setup menu and do a retune as well as check for any available software updates
Failing all of these attempts, then it would be time for the bin. There would be no economical repair option, as parts are no longer available for this system, and even if they were you'd spend more on labour costs than you would to replace the entire unit with a new one.