How to retrieve yahoo offline messages?

1. In your Contact List, find the name of the person with whom you were having the conversation that you now would like to review. Double-click their name in your list to open a Conversation Window. (Don't worry, they won't see anything or get any message.) 2. In the window where you usually see your IM conversations, click Show Recent Messages. Ta-da! Your most recent conversation with them appears in the window. 3. If you want to view an earlier conversation you had with this person, scroll to the top of this one and click View Full Archive. And if you'd like to not save conversations, or would like them to be deleted each time you sign out, then click Archiving Preferences to make an adjustment. The "Message Archive" window can also be opened at any time from the main Yahoo! Messenger window by opening the Contacts menu and clicking Message Archive. By default, archiving (saving messages) is turned on when you install Yahoo! Messenger. This saves all your conversations so you can refer to them later. You can change this setting anytime in the Preferences dialog box. Here's how: 1. Click the Messenger menu, and select Preferences. 2. Click Archive. 3. Click the button for the archiving option of your choice, and click Apply. Then click OK.

I don't think you can.