If you manage your Office 365 user accounts through the Administration portal (i.e. without using Directory Synchronization), it is now possible for you to restore delete user account.
A deleted account can be restored by yourself for the next 30 days after the deletion.
To restore user account, go to the Administration Portal, then browse the User management section (on the left menu).
On top of the User Management page,n a new tab is shown Deleted
Then the list of deleted user account is shown; just select one or more user account to restore and click Restore; of course, in case of Directory Synchronization use, deleted account can be used for synchronized deleted account.
User account and associated data are now restored.
For more details
- Restore user account for Office 365 Enterprise http://onlinehelp.microsoft.com/en-us/office365-enterprises/hh534386.aspx
- Restore user account for Office 365 Small Business http://onlinehelp.microsoft.com/en-us/office365-smallbusinesses/hh534382.aspx