Windows 10: Explorer.exe "class not registered"

I remember having made some changes in Windows/system32 andsysWOW64 where I changed the file extension of the file"ExplorerFramae.dll to BAK" in both the folders and also copied theold file "ExplorerFrame.dll" as before,in bothe folders which was doefollowing instructions on net which became necessary as I could start Starttab,Search option tab,Microsoft Edge and almost all the links to other programson task bar including internet and for most of these when clicked to open theerror www popped up showing Explorer.exe in the upper line and" class notregistered." in the middle part.So,nutshell because of these issues I hadto look for a solution which after trying a few I got attracted by changing offile extensions (as stated above) from dll to BAK but also replacing dll fileextension in both the holders.
After doing this change the PC is not booting/ going further then log in frame but when log in it just go to a black screen with result that I can boot/login.
Shall appreciate any help to fix this situation

:)

 

error messge

I had to do a system restore last night. After doing so, nothing in Windows 10 seems to work. When I attempt to open "Start" or "Store" or "Notifications" I get an error message {X} explorer.exe then "Class Not Registered". What should I do> The system
restore went back to right after 10 was installed. Thanks for ay suggestions. R. Michael Maddox

 

Explorer.EXE class not registered!

Try performing a repair upgrade:

How
to: perform a repair upgrade using the Windows 10 ISO file