2002 Ford Focus LX turns over but won't start

I was driving my 2002 Ford Focus and as I
was driving it stopped. I couldn't give it gas
and it was difficult to turn the steering wheel
too. I did experience a few "stutter steps"
within the month prior to it dying and when
idling sometimes it would seem like it was
going to turn off. When I had a mechanic
look at it, we discovered I had bad spark
plugs. We replaced the spark plugs, wires
and ignition coil but it still won't start. I can
hear my fuel pump so I don't think that is the
problem but I don't know what else it could
be. My mechanic suggested that I get a new
timing belt. Are there any other things the
problem might be?