I have a 2001 Pontiac Sunfire with automatic transmission. My left headlight was dim so I replaced it with a new bulb. This did not solve the problem. I decided to replace the battery as it was time anyway. Only a day after thismy car would not start and I had not left anything on. It started after jumping it. Again today my car would not start. What could be the problem here? I didn't know if it was a bad connection or a bad alternator. Please help!

You have a short. Or if you didn't jump your car right you coulda fried your alternator. But to be sure it isn't your alternator. Take it down to Autozone or Schucks and they can test it for free. But most likely you have a short somewhere in your left headlight wiring.

Follow the left head light harness through to rad cradle and just below the battery for corroded wireing that should fix your head light.