That often happens - when things fail - good one moment and not good the next.
How can you fix it? That's a big, big question.
The flippant answer is learn electronics - get the tools and test equipment - the circuit schematics. Diagnose and repair. a long process for you.
You could take to to a workshop to have if repaired but that would be costly. You might check the connections and fuse in the plug - just in case. parts and labour for a workshop repair could easily exceed £100
The other option is to buy a new one. Amazon are selling new 19" TV sets for as little as £120.
Good luck...
Peccavi
February 2013
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix televisions.