I think I'd go for a repair install.
If you don't have Win 10 install media you can do so by hitting the Download tool now button in
https://www.microsoft.com/en-gb/software-download/windows10 after reading the section in how to create installation media.
When done, open Windows Explorer - This PC - insert the media then double click on that drive where the process will begin.
You get the option to look for updates, but I opt out of that and let them download when the repair has completed.
I always disable my antivirus program and Ethernet connect before starting the repair install, so that the AV program doesn't interfere with the install and the machine needs to be connected to the Internet throughout the process.
This process won't affect installed programs or your personal stuff but you can sometimes lose the IE icon from the Taskbar, so you'll need to pin it back.
If you are using an upgraded machine then it may install Win 10 drivers on some of your devices and if your previous OS drivers worked better then you can go back to those.
That is done by going to Device Manager/View/Show hidden devices - expand whichever you want to check, right click on the adapter and select Properties and under the Driver tab you can see the date of the driver.
To go back to an older and possibly a better driver, right click on the adapter and select Update Driver Software - Browse my computer - Let me pick....
That may list all sections or just the drivers for that device.
If it lists all sections then scroll down to the applicable.
In the list of drivers for that device, click on your choice then on Next where it will install.
The repair install will put a Windows.old file onto your system which will be about 19GB.
This can be removed by going Start - type disk cleanup then press enter.
When it has run and shows what can be removed, click on Clean system files where it will run again.
Some boxes will still not be default checked, but these are the ones you can include for removal.
http://www.howtogeek.com/266337/what-should-i-remove-in-disk-cleanup-on-windows/When you have removed a large amount of files then it's best to run a defag.
You can do this by opening a Command Prompt (Admin) and enter defrag /c where it will analyze all volumes and optimize where required.
When you are back up to where you are satisfied, create a system image onto external media and continue to do so whenever you add anything to your system.
