Cas server uninstall failed... Now how to reinstall?

Ok, here is the scenario a company set up an exchange server and IIS config got damaged. So I followed the microsoft guide on uninstalling IIS then the cas server only problem was the cas fail the uninstall about half way through now I can't uninstall or reinstall.

Also can't reinstall the OS....

Any Ideas.

Output from installer:

Client Access Role
Failed

Error:
The following error was generated when "$error.Clear();
          $CommandAppCmd = join-path $env:SystemRoot System32\inetsrv\appcmd.exe;
          Start-SetupProcess -Name "$CommandAppCmd" -args "uninstall module exppw";
        " was run: "Process execution failed with exit code 1168.".

Process execution failed with exit code 1168.
Click here for help... http://technet.microsoft.com/en-US/library/ms.exch.err.default(EXCHG.141).aspx?v=14.1.218.11&e=ms.exch.err.Ex88D115&l=0&cl=cp

Elapsed Time: 00:00:01

Thanks in advance