I just bought a 2009 chevy hhr . It started fine and drove fine for a while . Then it started too not want to start . After I cranked it over a few times in morning it would start . Took it too advance auto and had it checked because engine light would stay on . It read mass air flow and o2 sensor . The maf was unplugged . Started running fine . Engine light stayed on . Had been run with no air filter . Went out to start and wouldn't. Changed plugs 2 and 4 where totally fouled out with fuel . Am going too change o2 sensors as soon as they come in ups . Could this have damaged the computer . And ruined engine .Please help

 

Why not get the codes read again then post the code NUMBER, not the description the kid reads off. My guess is a blown fuse NOT bad sensors.

 

Welcome to the site, I have moved your post to a more appropriate area to get you answers.
I don’t think you have a ruined engine, you do have a neglected engine.
pull the spark plugs and do a compression test, and do a fuel pressure test, your can rent/borrow tools from your parts store. While you’re there have those codes read as suggested.

 

Sounds like it did not run with MAF connected but OK when not? If that is so then the MAF is bad. The light will never go off with the MAF sensor unplugged.