why has my car lost power?

i was driving a long the road and started going down the hill, when i went to accelerate there was no power and the car wouldnt go. it is not the battery as all of the electronics on the car...stereo, lights, dash were all fine. i managed to get it into a car park but when trying to start it it just squeled. and the engine wouldnt fire. there was just a loud squeling sound and thats it, the electronics work fine. so its not the battery. any ideas??? thanks BTW its a Peugeot 206 LX 2003 1.4 16v petrol manual. thank you