Guarantees (and �extended warranties�) provided by manufacturers or retailers do not usually add anything to consumers� rights. Terms and conditions set by them cannot overrule the provisions of the Sale of Goods Act and under this act goods must be, among other things, fit for purpose and of reasonable quality. Neither of these is defined under the Act and it is ultimately up to courts to decide what is appropriate in each case. In your case it is a question of how long you can reasonably expect a TV set to last.
An EU directive in 2002 gave an absolute minimum of two years for all goods purchased in the EU:
http://ec.europa.eu/dgs/health_consumer/librar y/press/press31_en.html
However, in many cases that have come to court in England and Wales it has been ruled that it is reasonable to expect electrical goods to function properly for up to six years from purchase.
In any case it is the retailer who has the responsibility for remedy. The remedy may take the form of replacement, repair or compensation and the choice of which of these is suitable is the customer�s.
You do not need a receipt to pursue a claim. You will need to be able to show (or at least state) where you bought the TV and when. The retailer cannot simply dismiss your claim because you have no paperwork, but it may make your task a little more difficult. A chain such as Comet keeps comprehensive sales records and they should be able to trace the transaction from your name and address.
They will almost certainly try to suggest that as the manufacturer�s guarantee has expired then nothing can be done. You must stick to your guns and be prepared to pursue the matter through the small claims section of the County Court if necessary.