Chris

Right, so it is a basic Freesat box, requiring only one input from the LNB. I now see what you're meaning about connecting the other cable to the TV. The other socket on the wall plate claims to be providing signal from a terrestrial aerial and is really nothing to do with this issue.

Does the TV socket provide any signal? If you connect direct from the wall socket marked TV, into the back of your TV, can you make it tune in to Freeview (i.e. terrestrial digital, not satellite digital) channels? If you can at least tune your TV into Freeview it will get you going with some telly while you try to solve the Freesat problem.

As others have said, you have two cables to play with there, so try them both to eliminate the possibility that one of them has failed. Try each cable in the pair, and try them in both SAT1 and SAT2. Try all the combinations you can, in order to try to establish which part of your set-up has failed. Also, if you are on friendly terms with one of your neighbours, you could try plugging your Freesat box into their TV/wall socket, or if they have one, let them plug theirs in in your flat.

There are so many different things that can go wrong here but it almost always comes down to a broken cable (usually the plug comes loose and bits of fine copper braid start to short circuit) or a broken LNB (because it gets beaten up by weather and doesn't last forever).