Account Password Expired - Black-pearl Wont Start Repair Error error starting host server bind faile

All was well till 20 Dec. On 22 Dec, I noticed K2 workspace/designer/Smartforms/K2webparts in SharePoint are out of service. Account paasword reset - Still issues persist.
Next I tried to run the K2 Setup manager to repair the environment, on the website bindings page I get the below error.

The following exception occurred:
Object reference not set to an instance of an object.
StackTrace: at SourceCode.Install.Common.Classes.Certificates.GetCertificateSubject(X509Certificate2 cert)
at IIS7WebFunctions.BindingHasSpecificCertWithNoHostheader(Binding b)
at IIS7WebFunctions.SiteHasWildcardBindingWithNoHostheader(String siteName)
at SourceCode.SetupManager.UI.Common.Website.DoUrlBinding(Form parentForm, VariableBundle variableBundle, String siteName, Boolean mustHaveDefault, Boolean alwaysShow, List`1 reservedPorts)
at SourceCode.SetupManager.UI.Panels.WebsitePanel.FinishPanel()
at SourceCode.SetupManager.Main.navigateNext()

Next I changed the account name and password in these areas, IIS/K2 service/Etc.

Next checked IIS logs "Application pool K2 blackpearl has been disabled. Windows Process Activation Service (WAS) encountered a failure when it started a worker process to serve the application pool."

When i try to browse the K2 site from IIS manager I am able to go to the default page provided the authentication involves 'anonymous access - enanbled'. Else I get this error 'IIS 8.0 Detailed Error - 401.2 - Unauthorized - You are not authorized to view this page due to invalid authentication headers.'

Next I tried to continue the K2 setup manager repair by selecting the option 'select new site', i am able to move forward. So i guess the issue is with the existing site which K2 server is consuming. Any way i can restore the credentials anywhere which will let me bring back this environment?

BTW this is a development server, so the K2 blackpearl doesnt run as a service. Any help highly appreciated.