Need to Unlock AD user Accounts Automatically

Dear All,

We are getting Tickets of more than 500 counts for Unlocking  AD user Accounts & which is spending lots of time & efforts for it. So is there any  tool / utilities  or any integrated Administrative console by which we User can himself unlock & change the password himself.

Ex- Citrix password  management console which integrates with the AD & does unlock & change the password.

Thanks & Regards,