Our Sanyo LCD 32xr10f Tv showing screen saver message. We changed the cable to the aerial wall socket, but still not working. Tried retuning but got 0 channels, seems like no input signal.

If the tvs share the aerial but only one is working then the wiring of the non functioning socket has shorted. Perhaps the cable you used to connect the second set is damaged,try another. PERHAPS THE AERIAL SOCKET HAS BECOME DAMAGED,THIS ONLY COSTS A FEW PONDS/DOLLARS TO CHANGE. Alternatively it might be the wiring from the roof to the wall socket that is faulty.
First things first, check that the tv is working by connecting it in the other room. If it does work there you will know that theaerial socket in the second room is faulty and can begin testing.

You don't say whether you have had it working at that location before. When you move a TV between houses, it is necessary to retune your channels. Would recommend returning to first time installation.
If you haven't moved it recently there are other reasons why this might happen. 1) There is damage to your aerial caused by weather, 2) A power surge or loss of power to the memory battery on your video board has wiped the frequency information from the memory [the memory battery is like a watch battery that keeps a small amount of power going through the system to it can keep your settings when unplugged], 3) The internal tuner board for your TV has packed in.
If '1' is the case, obviously you need your aerial fixed; if '2' is the case you need to retune again [you'll know if the battery is dead if you have to retune every time you turn on the TV]; if '3' is the case you either need a replacement AV board or someone to solder a replacement tuner board to it.

Check the cable connectors and the connectors on the wall and TV to make sure the cat didn't break any of them. (It seems odd that a cat would be able to pull a coax connector loose - maybe antenna cables in the UK aren't threaded as they are in the U. S. A.).

Sounds like tuner fault. Check and replace it. If you wish to get some details; visit the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/

TRY AND RETUNE .THIS IS DONE IN THE LCD MENU

Go to the menu on the TV and auto retune this should fix it.
But first check the aerial is connected into the back .
No doubt you have various devices such as a DVD wired in? connect the aerial direct from the input wall socket and try that first.
When I get called out to fix TVs I normally find it's a cable fault mainly scarts not seated correctly or poor fittings on the aerial.
Hope this helps.

press menu on remote and re-tune tv (look in the instruction book)

The antenna socket is on the left side at the very bottom - in the back on the DP26-32648 model.
On the DP32649 it is near the bottom, with 3 inputs below it. So it is above the USB and 2 HDMI connections.

It may well be your aerial despite the success with your DVD recorder.

Digital signals are very much weaker than analogue ones, and when multiple devices share a single aerial you can get this kind of problem. You also lose about 60% of the signal at each point in your aerial cable where there are signal splitters.

There are a number of possible solutions:-

First, look at every bit of coaxial cable you have between the aerial and each appliance. Check especially at the aerial end for corrosion or poor shielding/installation and especially for evidence of rain water penetration. If the aerial is on the roof then it will cost almost as much to get the aerial inspected as it will to have it replaced, so skip to the next option. But otherwise, check along every bit of the cable for any cuts or splits in the insulation and properly remake every junction or joint if there are any doubts about them. If the cable is in poor condition then consider option three instead.

The second is to try to see if you get a better digital signal from another transmitter, this will involve trying different aerial positions so is impractical if your aerial is roof mounted but is worth trying if it's in the loft instead. It doesn't always follow that your best digital signal will be from the transmitter which you used for analogue transmissions.

Thirdly, if you're still using the same aerial as you have done for years then it's worth upgrading to one optimised for digital reception. When doing this it's foolish not to replace the cabling as well as you need it to be as good as possible. With analogue, many installers got away with using cheaper cable intended only for very short cable runs from the wall socket to the tv.

The fourth option is the budget option but can work as well as the third option: fit an additional analogue style aerials and run a separate cable down to each appliance. If these are fitted in the loft and you have the space, then there's no aesthetic or planning concerns. Normally the extra cables can run partway down through the house alongside existing cables, but for best signal quality keep them separate and ensure that the cable runs as as short as possible.

One further thing which you may want to try before all else: connect your digital box directly to the aerial cable which currently feeds your dvd recorder. Leave all other tv devices disconnected from the aerial. If the box retunes correctly then it's definitely a supply of signal issue as outlined above and if not then you should add the exact make and model of your digibox as a comment to this answer as there are a large number of earlier digibox models which cannot retune correctly due to evolving standards.