What is the battery voltage out put with key off and key on?
In OFF, you should have 12.6+ volts
In ON, you should have 13+ volts
If not within spec, have the alternator checked and have the battery recharged.
If the alternator has been checked and is OK, then check for vacuum leaks. If no vacuum leaks are present, then check the ignition switch:
using a test light:
using a DMM(digital multimeter):
Whats the mileage of the car?
Do the checks I mentioned above. If vacuum leaks are present, fix them, and if it still wont start, check the ignition switch. One of the 2 is the culprit.
You need to verify that injectors are firing? First make sure that there is power reaching them. Then use a noid light to check for proper pulse.
What did you check spark with? Did you make sure that you have GOOD spark?
Also, before this issue started, why did the car fail? explain as thorough as possible,please.