The brake light switch can prevent you from moving the gear selector on an automatic transmission. I don't think it will cause the car to not start.

Do you have an automatic or manual transmission?

What is happening when you turn the key and the car will not start? More specifically, does the starter motor turn on to spin the engine vs nothing happening? Or will the engine not run on its own (the point where you release the key)?

 

I have not had any problems starting it now that I changed the switch. Don't know if it has anything to do with the computer on the car but it works great now