I erased my Mac and am unable to reinstall OS. I do not have a backup and want to reinstall to factory settings

Wondering which MacBook Air Model (Year) you are using.

This Apple Support article may help.

How to reinstall macOS - Apple Support

or

Erase and reinstall macOS – Apple Support

All the best :-)

Thank you for your reply, and added info., florafromlawrenceville

Now I'm no expert on this, and as Community members we can not speak for Apple.

However, seems to me that at Genius Bar they will look at the situation, lend a hand, or give advice freely,

If there is a cost involved (eg: dismantling / replacing parts etc.), they would give you a quote before going ahead.

Seems Apple does want people to be happy with their products.