First and foremost, please establish the reason for the deletion of the page. User talk:Stifle/FAQs/deletion reasons has more details.
If some other user deleted the page, please ask that user.
If the deletion was due to a deletion discussion (Articles for deletion, files for deletion, etc.), then please open a listing at Wikipedia:Deletion review. I waive any requirement to discuss with me beforehand. I carefully consider all my discussion closures before implementing them. If you leave me a message asking me to reconsider, I will just point you there anyway.
If the deletion was due to a copyright problem, you'll need to show that the page is available under an appropriate license.
If the deletion was for any other reason, I will generally consider undeleting the page if it was deleted in error or if the reason for the deletion has been overcome. That means that if an article was deleted because it was about a non-notable person, you have to have proof of their notability to show me, and so on.
If you want a page restored as a draft or in your userspace, please open a listing at WP:REFUND. This page serves as notice that I authorize any administrator to restore content I deleted for this purpose, at their appropriate discretion.
Note that arguments about deletion by reference to another article on a similar subject that has not been deleted will not be considered. Other stuff exists. At best, it will result in me nominating that other article for deletion too.
Once you've got all your details together, click here to leave a message. Please make sure you include the exact article title (case-sensitive).