98 s70 tuning up; now won't start

[Vikki]

ok... I have now replaced the spark plug wires including ignition coil wire, following the diagram in the Chilton manual very carefully. It still won't start. I haven't found any vacuum hoses disconnected but it does sound like there must be one. There is also a humming sound coming from the engine after the key is removed. It goes on for a minute or so, and with an audible click it stops. Any ideas?

Vikki
ps.. thanks for the help so far!