If it is a Mk2 punto then the power steering will be electric as said above. Some possible causes of the problem are:
1. Your battery is not holding the correct voltage (possible if it's on its way out), to check simply put a voltmeter across the two terminals, if it's over 12.5 volts with the engine off or over 13 volts with the engine on then it's probably not the battery at fault.
2. The torque sensors or motors could be faulty (located on the steering column) not too sure how to check these.
3. There could be a break in the circuit, possibly a blown fuse.