There might be a salt option for reinstalling the templateVM from local data, but I’d suggest just backing up and then re-doing the install for simplicity.
Not great that this broke your setup. If it recurs, hopefully someone can help diagnose here.
Sorry to hear you’re having so many problems, @Sofiane. I’m not sure why this is happening in your case. FWIW, many other people (including me) are able to use Qubes without such problems, so it’s definitely possible. My only guess is that your hardware isn’t fully compatible with Qubes. Given your bad experience, I wonder if it would be better for the Qubes installer to just refuse to proceed if certain compatibility checks don’t pass rather than allowing the user to have a broken experience.
Have you gotten some libxenlight error in the post-reboot setup while it was setting up networking? That sounds like the same error i got when i used the latest installer.