DVB channel tuning not working oN Panasonic Viera but OK on other TV

After retuning my Panasonic Viera tv I lost about 60 channels, have retuned several times since so it doesn’t seem to be ‘atmospherics’ and no Freeview signal problems have been reported in my area (London). All digital channels are still available on the other TV in the house (a Samsung) . Panasonic tv is about 3-1/2 years old.

I retuned because I got the ‘new channels found, please retune…’ message on the TV set.