Microsoft has decided to force-feed Windows 10 updates, as a “recommended update” which will not only automatically download, but also actually upgrade your system to the new OS. I think this is a mistake, but since there is no longer any adult supervision in Redmond, it will probably continue.
If you’re caught by the Windows 10 forced-upgrade, here is how to get Windows 7 (or 8.1 if that’s your flavor) back.
Go to Start -> Settings -> Update & Security -> Recovery and you should see an entry on the right for “Go back to Windows 7” (or “Go back to Windows 8.1”). Click “Get Started” and follow the directions for “Keep my files.”
Figure it will take at least an hour, maybe two or three, and when it’s done you should be back, but you’ll have lost somewhere between 5 and 25 GB of disk space (which can be purged later).
Now – if you have a laptop machine, you may just want to play for a bit with Windows 10; I’ve found it to be a noticeable improvement over Windows 7, especially as far as managing battery life. But depending on your system’s age it may take a week to get all the necessary updates so that everything is working.
Otherwise, if you want to stay on Win7 (or 8.1) for a while longer, go get GWX Control Panel and make the headache go away.