2000 Other Fiat Models

I bought a car today, it started first time. I test drove it round the block for a test drive and it seemed fine. After driving it home (an hour and a half) i stopped to get a gate pass and then the car wouldn't start. A couple of lads bump started it and the car got me home. When i got home I stopped the car and then tried to re-start it but it didn't work. I went out an hour later and tried again and it worked!! What is wrong with the car??