Hi,
Thanks for posting in Microsoft TechNet Forum.
As you mentioned above that you can't download anything from Microsoft, I may need to confirm the following information.
1. Do you download these files through Windows Update or from Microsoft's websites?
2. When did you receive this error code, during the downloading process or during the installing process?
3. Based on my research, this error code is mainly related to Windows Defender. Were you running Windows Denfender while receiving this error message?
Moreover, to troubleshoot this kind of Windows Update issues, Microsoft has released a hotfix to reset the Windows Updates components automatically.
How do I reset Windows Update components
http://support.microsoft.com/kb/971058
For references:
Windows Update error 0x80240029 occurs when you try to update Windows Defender
http://support.microsoft.com/kb/934562
Hope this helps. Thanks.