The only real way to open files that are unsupported by the software you are using is to convert the file type into one that is supported. Conversion ensures that the file remains intact and you can still open it with the program you want. You can do this with online conversion websites. Many of these sites are completely free to use.
Visit a conversion website such as Free File Convert or Convert Files (see Resources).
Click on the "Browse" button on the site. A pop-up window appears. Double-click on the unsupported file that you currently cannot open.
Click on "Output Format." Choose a format that will be supported, based on what type of file it is. For example, if you have a "PDF" file, this is a document. A more common document type is DOC. A more supported music type is MP3, and AVI is one that may work better for video.
Click on the "Convert" button. Wait for the site to load. A link will appear. Click on it to download your new, more supported, file.