After upgrading the OS from Windows Server 2008 R2 to Windows Server 2012 R2 I found that all IIS websites and app pools were deleted and was faced with the below message when trying to open IIS 8.5:
One or more problems have been detected during IIS upgrade. As a precaution, one or more IIS services have been disabled. Please review the following error messages:
Data loss has occurred
You upgraded your operating system or switched from one Windows SKU to another SKU, and data from the previous installation of IIS has been lost or copied incorrectly. As a result, the services W3SVC and MSFTPSVC have been disabled. Before enabling these services, you should review the latest IIS 7.0 compatibility information.
You will need to install latest windows updates first then enable the disabled WWW service as well as start other services that were stopped afterwards you should repair or reinstall CRM 2011 to recreate the CRM IIS website and application pool.
There are many articles on the internet showing how the install CRM 2011 on Windows Server 2012 R2 after updating the setup files like that one:
The 2 points to consider after the installation specially when upgrading from Windows Server 2008 R2 is to update the URL rewrite module to version 2.0 to be compatible with IIS 8.5 and ensure that the application pool account is having read permission on the CRMWeb folder.