how do I find out if a placed order was deleted or trashed? [closed]

WooCommerce order numbers are not sequential as the orders share WordPress’ posts table in the database. The posts table in the database is shared with posts, pages, draft posts/pages, images/media etc.

So, if you had an order and then a post, page, draft or image was created then it would have taken, in your example ID #2099. Then your next order was stored as ID #2100.

If this is a problem for you then there are plugins available that will make your order numbers sequential to help prevent any confusion in the future. One example is – WooCommerce Sequential Order Numbers