Wordpress Theme Update Doubt

Hi,
I'm using contentberg theme which download from Envato elements. There is no issue till yesterday.

Yesterday I checked my blog. WordPress new version 5.5 database updated. After WordPress update my theme completely collapsed now. I don't know how to retrieve it.

I'm not a developer. I just customize the theme only.

Someone said, need to upload "Child theme". I don't know how to upload it. I have FTP access for my blog.

Can anyone guide me to get back my theme?

FYR: I have attached the currently active theme and Contentberg child theme files

Archive the child theme files in a .zip and then from WordPress dashboard, go to Themes > Add New > Upload file

That should activate the child theme.

Edit: If that doesn't work, roll back to previous version of WordPress using this plugin - https://wordpress.org/plugins/wp-downgrade/

Reach out to theme developer and confirm if the theme is compatible with latest WP update. And do not forget to take complete backup.

@FlipDime Thanks.

I just replaced the function.php (from child theme) folder using FTP. My theme is back now