You can also run the System Update Readiness Tool (KB947821) from Microsoft’s download center. This tool fixes servicing stack corruption that causes activation errors.
If the status remains unavailable or the product key is rejected, users can utilize the system: how to fix windows 7 activation status not available
This error frequently appears on or Professional (Volume) editions that were previously activated via a KMS (Key Management Server). If the KMS server is offline or unreachable, you get "Activation Status Not Available." You can also run the System Update Readiness