Yea I have a similar problem with my project car, it started one day and the next nothing, I also think it's the fuel pump after removing it and testing it, it seems dead, I couldn't say exactly were your switch is or what it looks like on your car as I'm not familiar with fiestas, but let's say it's the same as a focus, it's a black plastic housing with a round red plastic button under the drivers side carpet to the right of the pedals, really easy to find. If it's activated it would have come up and be level with the top of the black plastic surround, if it hasn't it will sit about 15-20mm further down. You can also try disconnecting your battery for 10-20 minutes and this is thought to reset the ecu in many cars, how true it is I don't know but again it's a free and quick thing to try.

This is the fuel cut off box your looking for and in this picture it seems to be inactivated.

http://www.ebay.co.uk/itm/FIESTA-ZET...item35c94b830c

To test the fuel pump you'll find it easier to have someone to help, you'll need to gain access to the fuel pump plug and may mean removing your fuel tank, take your multimeter and ground the black pin to the body of the car and put the red one in one of the pins on the plug, get some one to turn the key to its ignition on position and see if any power comes through for it to prime the pump, at a guess I'd imagine your looking for around 12v, do this with each wire until you find the right one also repeat that process with them trying to start the car to see if you get a permanent live, make sure your fuel tank is right out the way when working on the electrics, if there's power as normal I'd be safe in saying the fuel pump is nacked.