Start with the switch. A product only reaches your shop when its Active switch is on. You can see and flip it in the Status column on the Products page, without opening the product.
Then check the other four. A product saved with Save Draft is not published at all and waits in Drafts. A product with a Publish Date in the future waits until that moment arrives. A product with an expiry date is hidden once that date is reached, or earlier if you set Expiry Buffer Days in your settings. And a product whose category is switched off cannot be reached by anyone browsing that category, so check the category too, especially if you switched off a main category and its products went with it.
If none of your products show, check that your store itself is published. Once the store and the product are both live, the Products list shows a View in store link beside the product name that opens its page.
One thing that does not hide a product: running out of stock. It stays in your shop, marked as out of stock, and cannot be added to a basket.