Since the change happened because you followed a windows prompt, this should help at least for the default file associations.
How to change or restore the default file associations in Windows 7
https://www.wintips.org/how-to-change-restore-default-file-associations-in-windows/
Thanks Bob,
I was able to associate Google Chrome as the Default Program and then clicked OK.
I think we are getting there. I noticed that my .lnk file extensions are all linked to Avast Driver Updater. When I go into the Set Default Program - Set File Associations. A list of File Extensions appears. Many seem correctly associated. When I scroll down to the alphabetical list of extensions, next to “.lnk” extension is Avast Driver Updater UI which is listed as the Default Program used to open all .lnk file extensions. I believe this might be the root problem as to why all my short cuts point to ADU web homepage. Can you advise? What program should be the default program for .lnk file extensions in Windows 7? Thank you for hanging in there with me Bob.
…Bill
I’m using Windows 10. lnk has no fill association on my system and I use the Avast Driver Updater.
https://d1ka0itfguscri.cloudfront.net/Lh/2021/06/14/14/19/cr122qV1c1s/preview.jpg
Have you reset the default associations as suggested?
I selected Google Chrome - Set this program as default - OK.
I have not restarted my computer though. Should I?
a .lnk represents a shortcut. A shortcut to chrome, would be associated to Chrome
A shortcut to something else, would not be. If there is a shortcut to a video, you want that to be opened by your media player not Chrome.
So, Chrome is not the correct association for lnk.
That’s why I asked if you had reset the default associations.
When I go to the list of file associations, they all appear to be correct except “.lnk” which has Avast Driver Updater UI as the current default program. When I click on change program, I don’t see a way to remove it, only to change it to a different program.
Which is why I asked if you’ve reset the associations to their defaults.
Follow the instructions here, https://www.wintips.org/how-to-change-restore-default-file-associations-in-windows/
I have 13 default programs listed. They are all set to default except the other 2 web browsers and Quicktime.
Re-read this post.
https://forum.avast.com/index.php?topic=280226.msg1626901#msg1626901
I don’t know how else to explain the fact that assigning an action to shortcut is not what you should be doing.
It needs to be set to default
I understand this. Why do my shortcuts all lead to Avast? When I right click on a program, lets say Logitech Mouse (which works btw) the little pop up box says the file type is “(.lnk)” and the little icon is not a Logitech icon, it is Avast.
Because you assigned the Avast program as the default for all lnk (shortcut) files.
I need to somehow un-assign the .lnk file from Avast Driver Updater. The run command opens Avast. The System Restore button gives me an error message saying it could not open it.
Follow the instructions to reset default assignments. once that’s done, you can then set any thing that opens with a program other than your favorite to that program. You can’t unassign all you can do is assign so you need to start with the default settings.
When setting programs to default assignments, Chrome and Firefox compete with each other. For instance, Firefox has 0 out of 13 defaults. I can set it as a default, but then Chrome has 10 out of 23 defaults. So, have I followed the instructions and reset my default assignments? Yes…and no. 
And, the same thing happens between Windows Photo Viewer and Paint.
Resetting defaults re-assigns all the default programs which includes shortcuts.
You can only have one default for any program that includes your browser.
You can always open a different browser on your own but, if you click on a link which opens your browser, it will open your selected default browser.
It seems that I have very few programs (11) listed when I click “Set your default programs.”
Just an update for anyone reading this thread. I am still working on the issue via email with Avast Support team.
…Bill
My file extension issue has been fixed. I’m not sure what exactly the technician did, but he ran a program that changed my program files back to .exe. This was at the Geek Squad which took making an appointment, bringing the computer in and approximately 1 hour of bench time while a waited and watched.