Jack had to replace his hard drive. He updated to Windows 10 and rolled back to Windows 7, but now it won't update any fixes. Leo says this is another reason to not buy a Windows machine. This happens when an update gets blocked or doesn't complete and until it does, you can't get the next update.
Jack could just reinstall Windows 7 and start again. That's the easiest way. He can try resetting the update here with these instructions from support.microsoft.com, but it may be easier to just start over.