Your friend probably saved them in HTML format by mistake.
Save the files to a convenient location on your hard drive first (rather than trying to open them directly from your email). Don't worry if they're shown as being HTML documents.
Go the location of the files, RIGHT-click and select 'Open with'. Choose Microsoft Word or whichever other word processor is on your computer. Then go to File > Save As (not just 'Save'). Change the file format to 'Word', 'doc', 'docx' or whatever your word processor calls it. You'll then have the files back into normal Word format.