Someday, an article you created or worked on may be deleted, and you won’t know or won’t agree with the reason for the deletion. If so, remember that very little is actually deleted in Wikipedia—it’s still visible to admins, just not to regular readers. And Wikipedia’s processes are not infallible, so you have some options.

First, read Wikipedia:Why was my page deleted? (shortcut: WP:WWMPD). Among other things, this page explains how to find out why an article was deleted. If an article was deleted as a result of a proposed deletion, any administrator will usually restore it upon reasonable request. Follow the link at WP:WWMPD to post such a request.

A second option is to try to persuade the admin who made the deletion that it was in error. This option is worth trying only for CSD deletions, since prods can be reversed by asking, and AfDs won’t be reversed just because you ask nicely. Before you make such a request, do your homework—does the CSD deletion really seem unreasonable? Don’t, for example, argue that the deletion was wrong because the article could have been fixed. CSDs are based on what was actually in the article, not the article's potential.

Another option is simply to start over. If the article was short, you’ve really not lost much if it was deleted. (You might even find a copy at Google—click the Cached link rather than the main link.) Just be sure that you start the article in your own user space, and don’t move it to mainspace (where all regular articles are) until you’re sure it can survive on its own. CSD criteria G4 allows the speedy deletion of a “substantially identical” copy of any article deleted via AfD, particularly where the problems identified in the AfD discussion have not been addressed.

Sometimes you might acknowledge that the deletion was probably right, given the shape the article was in, but you think you could fix it. If so, and if you can’t find a cached or other copy of the article to use as a starting point, you’re not necessarily out of luck. Check the page Category:Wikipedia administrators who will provide copies of deleted articles, and make your case to one of the admins (check his User contributions page first, to make sure he’s still active). Ask that a copy of the article be put into your user space, as a subpage. If the article wasn’t libelous, a massive copyright infringement, or an attack page, you’re likely to succeed.

Finally, you can initiate a deletion review process, at the page Wikipedia:Deletion review (shortcut: WP:DRV). This page is for appeals to restore deleted pages (and also for appeals to delete pages which were closed as “keep’” in an AfD discussion). Before you do so, read the section, “What is this page for?”, which explains that DRV is for cases where you believe the process was wrong, or where “significant new information has come to light.” DRV is not a place to say that you didn’t like the outcome, or a place to go in the hopes that a new discussion can occur that’ll lead to a different result.