Machine spontaneously DOWNGRADED to Windows 10 Pro Insider Bld 10565

Microsoft Windows [Version 10.0.10565]

You are now 4 insider preview builds beyond the RTM build Version 10.0.10240.

You are actually "upgraded" to build 10565 from 10240 - not downgraded. What you can try to get back to build 10240 without losing anything is this:

Download the ISO file for Windows 10 Pro build 10240 using the Windows Media Creation Tool:
Windows 10

Mount the saved ISO file by right clicking on it and selecting Mount.

Make a new folder on your hard drive - like Win10 or whatever you want. Copy everything from inside the mounted ISO file to the folder you created.

Go to the Sources folder inside the files you copied. Edit cversion.ini file. It should be:

[HostBuild]
MinClient=9458.0
MinServer=9458.0

You want to change it to read:

[HostBuild]
MinClient=10.0.10565
MinServer=10.0.10565

Save the edited file. Go back up to the folder you created and run setup.exe from it and try to do an "upgrade" over the top of your current Windows 10. Then in advanced options under Windows Update make sure you do not have insider builds turned on.

I am confused now. Will the Windows 10 ISO allow me upgrade to full Windows 10 from 10656?

As a windows insider you are now 4 builds above the "full windows 10 ". It would help solve your problem if you could tell us if you meant to be in the insider program.

Oh my, now I see.

Problem solved. I'm just a little slow. Yes I will stay in the insider program.