No Compression, No Spark

Hi,

On my 1991Corolla, 4A-FE 4-cylinder, the engine turns over with little
noise, so I suspect no compression due to a bad timing belt.  I
checked for compression and their is none, checked for spark, none as
well.  It seems like a timing belt issue, but I am not a mechanic,
(just die hard DIY).  What bothers me about my diagnosis is how the
problem unfolded; i.e. don't timing belts go bad when you have the
engine running/driving, etc and not after the car has been sitting for
hours?  Plus when it goes, doesn't it fully fail, without out
warning?  In my case I noticed the problem as I started my car after I
got off work (after it had sat for 9 hours), something seemed way
wrong, (no compression) then after 20-30 seconds of cranking where it
sounded as if there was no compression, it came back to "life;" i.e.
sounded like it normally does when cranking and then started up.   On
the drive home, I made a 1/2 stop and the engine restarted fine and I
also turned off engine at some point to see if it would start, which
it did.  Then the car sat over night and the problem was there again
when I tried to go back to work, and will not start up for good this
time.  Hence with that slight amount of intermittent failure, does
that point to something else (and hopefully easier to fix) or is that
typical of a timing belt failure?  And if not the timing belt, what
else could it be?

Thanks for your help.