How Do I Fix Credential Issues In Lync?

Lync 2010/2013 stores credentials when you initially set it up. This might lead to connection issues after resetting password.

Here are the steps to fix the issue (close Lync first):

Remove the certificate

1. Go to Internet Explorer > Tools > Internet Options > Content > Certificates
2. Remove the certificate issued by Communication Server under Personal > Certificates
   

Clear entries in Credential Manager

1. Go to Start > Control Panel > Credential Manager > Windows Credentials > Generic Credentials
2. Remove the entry with the following address: Microsoft_OC1:uri=username@domain.com:specific:*
   

Remove Crypto folder

1. Go to %System_Drive%\ProgramData\Microsoft\Crypto\RSA
2. Remove the folder S-1-5-*

Set the Communicator registry key to disable saving password

1. Go to Registry Editor (Start > Run > regedit > OK)
2. Choose HKEY_CURRENT_USER\Software\Microsoft\Communicator
3. Double-click the value SavePassword and set it to 0
   

After following all the steps run Lync again and enter correct credentials.

Ref: https://kb.intermedia.net/Article/3095