(Did I cause?) Sudden shut down, no start Options

[ActionClaw]

The car: 1995 Toyota Celica ST, 1.8L 7A-FE, standard shift

I was driving down the street, slowing to a light when -- as though an OFF switch were thrown-- the car suddenly shut down. Trying to restart, it'll crank but not turn over. It seems very similar (perhaps identical) to what I experienced years earlier in the same car when I ended up having to replace the distributor. I wouldn't be surprised to learn that this may be the case again. I've read this is a common problem with certain Celicas and the replacement distributor was from bone-yard.

...BUT...I had just done some work to the car the day or so previous and had only very briefly driven it once or twice since. This may be an unrelated, coincidental but, logically, I can't help but think that there may be some (direct or indirect) connection to the work I had just completed; something I forgot to reconnect, didn't re-tighten sufficiently, etc. I've looked it over, everything seems OK (and I have no extra parts left ). Maybe one of you might catch something I'm overlooking?

What I did:
Installed new..
..valve cover
..valve cover gasket, spark plug tube seals
..spark plugs
..spark plug wires

oil change, oil filter, air filter
(spray) cleaned EGR modulator valve
(attempted to) clean the EGR valve

I've only begun to start troubleshooting and I have to double-check a few things to be absolutely certain but, offhand, the problem appears to be no spark.

What might I have done to create this condition? Any ideas?
Thanks