What do you mean by "won't open either"? Zotero saves snapshots as HTML files to disk and simply opens those in your computer's default browser. If a particular snapshot isn't appearing correctly, there may have been a problem saving that particular page.
So my last paper if I clicked on one of my cited web sites from my library it would open the web page in chrome. I tried to do it today and suddenly it tried to do it on Microsoft edge web browser. I think it might be the way its saving it. If I try to cite and have zotero save with out snapshot it works just not sure what changed. I also changed my default browser to chrome so it would attempt to open in right browser but still any with a snapshot wont open at all.
It sounds like there's a difference between your default browser and the program associated with HTML files on your computer. That's why you'd be getting Chrome when you open a URL (when you save without a snapshot) and Edge when you open an HTML file (which the snapshot is). If you look up how to associate a program with a particular file type on for your version of Windows and do that for HTML files, you can fix this.
For windows 10, you can do the following to change the program associated with HTML files: On the Start menu, select Settings > Apps > Default apps > Choose default apps by file type. Then go to the line .html and select your desired browser.
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About the not opening -- what exactly happen? And does it try to open a local file or a URL? From where did you originally save the webpage.
On the Start menu, select Settings > Apps > Default apps > Choose default apps by file type. Then go to the line .html and select your desired browser.