How to reinstall operating system if it was wiped from the computer

How to reinstall macOS - Apple Support

If you are unable to proceed describe where you're getting stuck.

Should be easy enough- this model does support Internet Recovery.. so connect Ethernet via a cable, or adapter ( Ethernet port could be on the power adapter) adapter should be USB-C to Gigabit Ethernet adapter… or have strong WiFi network close by ( much slower though) restart MacBook Air holding down Option key *Apple/command key+R together on startup… you should see spinning globe and progress bar… when bar has loaded, you should be able to choose Re-install MacOS… the other way would be making a bootable USB-C stick with the MacOS installer on it, restarting, holding down the option key to get to Startup Manager, plugging in the USB-C stick… left and right to choose drives and click to select one… I’ve used Lion DiskMaker X successfully in the past to make one of those… what year is your MacBook Air ? That’ll determine which version of the MacOs you need… if you don’t know, there should be a model number on it somewhere on the outside… starts with “A” then 4 numbers/digits… take that info to Everymac.com and search using that model number… it’ll tell everything about your MacBook Pro

John B