Windows Server 2012 R2 - Error: Server Manager is collecting inventory data. The wizard will be available after data collection finishes

Please use try following approach:

open command prompt with admin rights and execute it as below:

cd C:\Windows\System32\wbem\AutoRecoverfor /f %s in ('dir /b *.mof *.mfl') do mofcomp %s

Once completed you can start Server Manager and start adding roles and features again.

CodeHunter