Step 1 : Login to your database using the PhpMyAdmin
Step 2 : Now search for the catalog_product_entity tables, Refer to the image below:
Step 3 : Now just click on the sql tab and runs the below query as per the screenshot below:
UPDATE catalog_product_entity SET type_id=”simple” WHERE type_id = “downloadable”
then it will change all the downloadable products into the simple products
Step 4: Login to your admin panel and see the changes into the products type.
You can do it for the configurable and for the bundle products also
Hope it would be the helpfull for someone. Keep reading and enjoy the Magento Coding.