Can't open .cab file

Question

I have a SharePoint Template that was created by a different developer I don't have the VS Solution for it. I downloaded it as .wsp file but I couldn't view it which made me change it to .cab I received the "can't open file" error. To solve it I used Easy 7-zip to extract it and the error was "can't open the file as [Cab] archive Is not archive.I also tried Start -> Run. then: msconfig.exe I couldn't "Expand File..." at tab General. I just want to read everything in the Template before even editing it, I know that would be a bigger issue. Any help or ideas are appreciated thank you.