The products disappear from your store administration dashboard because the default language of your store has been changed without following our standard steps.

If you want to return, the products to visibility in your dashboard, please follow the steps below;

Step 1: Go to the Settings->Language to change the default language back to 'English' and keep your own language(s) as additional.

Step 2: You'll be able to find all your products in the Catalog-> Products. Re-edit all the products as needed. 

Step 3: Change the default language to the language you wish.

Your products should appear in your product list now.