I went for a 2-3 hour Drive today round-trip In my 1999 Ford escort.Got home, Was home about an hour and took one more trip to Walmart. I came out of Walmart and the car ... It won’t start. But the really strange thing is the service engine soon light comes on when I turn the key on (again it won’t start), but when I turn the key off the service engine soon light stays on. Any ideas on what this is and how to fix it? Any help would be much appreciated. Thank you in advance!

 

There is a good possibility of a computer problem.
This is what would be described as a Hard Fault and shouldn't be too difficult to determine the cause.