How do you repair the speedometer of a Fiat Bravo when it only points 0 mile per hour no-matter how fast you drive?

Two possible problems.............. The speedo cable which drives the speedo is broken, or loose at either end of it. Or the gears inside the speedo head are faulty. You need a professional mechanic to fix this. Typical Fiat, my Fiat used to do this every time it was being towed to the garage aswell. Try getting the AA to lift it up by the back wheels instead, that should work mate.