Invaluable if you are unable to upgrade, or is impatient.
Yesterday's first Redstone 2 version is rolled out, but you might not have received it yet? Then Microsoft tool for you.
Let Microsoft do the job for you
Not only can the upgraded "Windows 10 Update Assistant" (download, direct link) help Fast Ring testers to get freshest test version, but it is also helpful if you are stuck on an older version.
The tool checks whether your computer is ready for upgrading. After this is done it downloads any updates. This takes some time. You can fine do other things while the download is in progress.
When the download is complete, the program that all files are in good health, and you're ready.