Kia stopped running

Prior to my car dying I was told that my
starter would soon need to be changed.

I was driving down the road (30-40 mph)
and the car just died on me. It made no
loud
noises it just quietly died, in fact I didn't
notice until I had put my foot down to
accelerate again. After my car died it
wouldn't start up at all, it made this
whirring
noise like something was rapidly spinning
but, it didn't sound anywhere close to
starting up.
I changed my starter since I assumed that
was the problem but after I changed the
starter and tried to restart my car the
whirring noise had only gotten louder and
the car still wouldn't start. I asked around
and was told that my timing belt needs to
be changed but I want to make sure before
pay lots of money to fix it.

Not sure if this helps at all but before the
car died it had problems idling, at least I
think that was the problem, when I would
come to a stop the car would shake
excessively but when I put it from drive to
neutral it would quiet down.
Please help.