I cannot find the product when I type the product name and code in the search ba

As you have already tried changing the theme, I suggest you try using a standard WordPress theme and disabling plugins. Some plugin might be altering the search query, possibly using the pre_get_posts filter, which could be why your search is not returning any results.

If those steps make no difference, I recommend getting in touch with WooCommerce’s support about this via https://woocommerce.com/my-account/contact-support/ if you have any of their paid WooCommerce products or https://www.ads-software.com/support/plugin/woocommerce/ if you do not.