Mac reverted me to original OS but wont install

I have a MacBook air (2010) that was happily running on High Sierra until I

decided that I wanted to do a clean install. Basically I started it up in

Recovery mode, deleted the sdd image and then went to the re-install High

Sierra (standard procedure which I've done before).

HOWEVER - for some reason it crashed on install so i just rebooted it in recovery, but

because it was half way through install I had to recover over internet which

was all well and good but of course it took me back to trying to install the

original OS which was lion 10.7. Upon signing into the App-store to download it

I got the message "This item is temporarily unavailable", now I’ve

downloaded and used this in App-store in the past but for some reason it’s not

available to me anymore, and  I tried it on several Apple ID's. I can only

assume they have removed it, but I’m not sure why as this situation gets people

stuck (i may be wrong though)

ANYWAY - I thought well the only thing left to do is download a bootable installer of

the most recent compatible version of OS with my mac which is obviously High

Sierra as i was using it before. So I downloaded a copy on a separate mac then

I followed apples procedure to create a bootable installer with a USB. 

 BUT - when I booted up the mac and to run start up manager it saw the High Sierra

bootable installer USB and started to load with the grey bar but then I just

got the stop sign on the grey background.

 This is where my knowledge ends, basically I’m left with a MacBook that wants to

install lion, but i cant download it and cant install High Sierra because it

won’t run the bootable installer successfully. 

Can anyone please please help???