This article uses screenshots from, and applies specifically to, Outlook 2013. However, Outlook 2010 has similar functions and a very similar interface, so these instructions should be easy to apply in the older version.
In order to restore the content of your email profile in Outlook, you will first need a PST backup of that content. If you don't have a PST backup, check out this article.
Restoring your content
First, open Outlook, then click on the File tab:
Then click Open & Export and Import/Export. This will open the Import and Export Wizard:
Select Import from another program or file, then click Next >.
Outlook now needs to know which file format our backup is in. We want to restore from the PST file* we created in the other guide, so choose Outlook Data File (.pst). Then, click Next >.
*If you have a CSV file to restore from, choose that option, then follow the on-screen prompts.
Click the Browse... button and select the PST file you'd like to restore from. Choose how you'd like to handle duplicates (in most situations, the default to Replace duplicates with items imported will be what you want), then click Next >.
Because we took a full backup of our entire mailbox, every part of our profile is available. For a full restore, simply select the Outlook Data File (If you only want to restore your calendar or a specific subfolder, select that entry). Make sure 'Include subfolders' is selected, then click Finish:
Outlook will now import all of your data. This may take several minutes; the bigger your profile was at the time of backup, the longer it will take to import.