@freddieomm, I suspect that the problem originally occurred because you introduced an error into the functions.php file. You will need to fix that or restore a backup of functions.php in order for your Genesis theme to work properly again. The reason that you can view the site using a different theme is that each one has its own functions.php.
I don’t know all that you’ve done in between to try and fix things but here’s what you could try:
1. Delete your Genesis parent theme and child theme completely from the server using FTP
2. Reinstall the Genesis theme from a fresh copy – you can download that from your StudioPress account https://my.studiopress.com/ and here are installation instructions https://my.studiopress.com/tutorials/install-genesis-child-theme/
3. Do the same to reinstall your Genesis child theme from a fresh copy (be sure to install Genesis first, and then install the Genesis child theme separately)
4. Replace the file in /themes/yourgenesischildname/functions.php with a backup from before you started editing it yesterday
That should get you back to where you were before you tried to make changes. If you had never modified functions.php before, then #4 is not necessary.