If you only deleted them then you would have to send out an add request to them to approve. If after you deleted them from your contact list, you also put them on the ignore list you will need to unignore them first. If you do not remember if you ignored them you can check the Ignore list which is in Preferences in the Messenger menu at the top of Yahoo Messenger. Choose the Ignore List category. Choose the bottom option, then look for their names on the list, if you find it select their name and click Remove.
