HiDaiweiYan**,**
You can try opening the files withNotepad or another text editor. Many files are text-only files meaning no matter the file extension, a text editor may be able to properly display the file's contents.
If you want only that file to open in the program this one time, clear the Always use the selected program to open this kind of file check box, and then click OK.
Refer to the below link for further information -
http://windows.microsoft.com/en-US/windows7/Change-the-program-that-opens-a-type-of-file
Hope this helps.