Windows 10 - ox80073cff Mail, Calendar, and People apps won't install

ox80073cff  

• In this build, the Mail, Calendar, and People apps may be broken due to a licensing issue with the Store Beta. To get these apps working again, you need to follow these steps:
• Open powershell as administrator
• Run the command Get-appxprovisionedpackage –online | where-object {$_.packagename –like “*windowscommunicationsapps*”} | remove-appxprovisionedpackage –online
• Re-install Mail, People and Calendar from the Store (green tile)

http://blogs.windows.com/bloggingwindows/2015/03/18/windows-10-technical-preview-build-10041-now-available/

If you now get this error 0x80246007 try running: from and administrator command prompt

DISM /Online /Cleanup-Image /RestoreHealth

Bring back the windows 10 start menu.

Just follow the steps below:

1. ​Right click on the Start Button and select "Run"
2. Type "regedit"
3. Navigate to HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Explorer>Advance
4. Create a new DWORD (32-bit) value, call it "EnableXamlStartMenu"
5. Restart Explorer​

Found from 

http://www.winbeta.org/news/how-bring-back-old-resizable-start-menu-running-windows-10-build-9926