I tried installing big sur on my MacBook air 2012 and damaged my Mac !!

[Juliana julianaa]

I tried to install Big Sur on my MacBook air 2012 and i something went wrong. When i tried to install high Sierra again it takes me only to Mountain Lion instead, i installed mountain lion and tried to update but i had a problem.
The app store doesn't work, itunes or any other app related to apple. My Mac was connected to internet since some websites work on safari but yet i couldn't update my Mac.
I've been searching for a week for solutions until I started believing that no one in the world can fix my problem.
I tried to fix the date and time as automatic but it's saying that it was unable to detect my location.
I even tried to create a new profile, to change DNS, i tried to change some things in the key chain. Nothing seem to work and app store keep saying "cannot connect to the app store"
please if someone can help to fix this in my opinion this person deserves a medal.
I'm a good browser and all the time i manage somehow to find the answer, this time I'm stick and they directed me to this website saying it's one of the best.
THanks in advance my dear friends.
PS : i don't have makintosh anymoreb

 

[barbu]

You should not have been able to install Big Sur. Your old MacBook is not supported, so the install would not have started in the first place.
I think we are missing some details. Did you wipe your drive? Does it still boot?

 

[MBAir2010]

TRY installing El captain over mt lion
that OS reads iCloud and can recognize your iPad, iphones
the you can go to high sierra and Mojave with a patch.

if you need more specific info, let us know!

 

[DeltaMac]

The 2012 MBAir does not need a patch to install Mojave. In fact, Catalina is supported natively.

@Juliana julianaa - best way forward is to use an external bootable installer for the version of macOS that you want.
El Capitan or later should get you going again.

 

[MBAir2010]

Juliana
did everything work out?