Did you have updated from X 4.6.4 to X 5.2.5? Please be advised that there have been a lot of change going on especially with WooCommerce 3.0.0 as they have changed several things in product images. I would suggest that you review the changes from our changelog here: https://theme.co/changelog/
And then regarding the product images, please review this thread:
Just in case you simply want to display the default product images without the product gallery slider and the product gallery zoom, please add the following code in your child theme’s functions.php file
add_action( 'after_setup_theme', 'remove_woo_features', 999 );
remove_theme_support( 'wc-product-gallery-slider' );
remove_theme_support( 'wc-product-gallery-zoom' );
By the way, product gallery slider and product gallery zoom is a new feature of WooCommerce introduced in 3.0.
Hope this helps.