Hello experts,

We have a Windows 2008 R2 server, we didn't enable recycle feature on it before and we don't have any backup. Some admin has accidentally deleted few usernames. Those users have Exchange 2010 mailboxes. 

Is there any way to restore those deleted users? If not, how to create new users and link them to the original user mailboxes? 

Hi Haythamk,

It is easy. A disconnected mailbox is an object Exchange store which is not linked to any user in AD.
You can link to another user.

EMC->Disconnected Mailbox .
Enable the disabled mailbox using Connect button on right Action page.
New wizard will open. There you will have to connect this mailbox with the new/existing user.

Please check below URLs as reference/steps to follow.

https://technet.microsoft.com/en-us/library/bb123490(v=exchg.141).aspx

http://exchangeserverpro.com/reconnect-disconnected-mailbox-exchange-server-2010/

Thank you. 

Is it possible to restore deleted user accounts? I think that, if I create new user accounts, then users will receive a clean desktop when they try to login again to their desktops.

I would allow them continue using their existing Windows profiles. 

Here you go
https://technet.microsoft.com/en-us/library/dd379509(v=ws.10).aspx

I have just checked (Disconnected mailbox) in EMC. I see only disabled mailboxes there. There are no mailboxes for users which have been accidentally deleted. Please note that user where deleted from AD users and computers, not from EMC.

The given link contains a way for restoring objects from recycle bin. Again, we don't have recycle bin enabled on this AD.

Its quite difficult but yes you can have a look at this link and they would help you for the same.
http://technet.microsoft.com/en-us/library/bb727048.aspx
http://redmondmag.com/articles/2012/01/01/how-to-fix-ad-disasters.aspx
http://www.techrepublic.com/article/backing-up-and-restoring-active-directory/

These articles are about restoring from a backup. As mentioned in my very first post, we do NOT have any backup.

Do you have other domain controller in the company? You may be able to catch the change before it replicates to all the other DCs copy the info and then try update the user account again.
There is no undo with active directory changes if Recyclebin not enabled

No unfortunately, this is the only DC as it's a small organisation and didn't do a backup yet. 

As configured by default, exchange server mailbox DB purges the deleted mailboxes only after 30 days of removal. So, how to catch the same? 

Please try this as well
https://technet.microsoft.com/en-us/sysinternals/bb963906.aspx

http://social.technet.microsoft.com/wiki/contents/articles/5549.recover-active-directory-deleted-items-using-ldp-exe.aspx

If above also fails your only option is to create new user and connect the mailbox to newly created user.
If the mailbox does not show as disconnected run the below command

Clean-MailboxDatabase <database name> 

Hi,

Any updates if you have resolved the issue ?

If you still unable to restore the deleted objects, you may also check this automated software (http://www.activedirectoryrestore.com/) that helps to restore all the deleted objects back into previous used format.