EXT4 is a linux file system and Windows cannot read it. You will need to boot a live linux disk to access the file and then copy it to your Windows computer. I would recommend Puppy linux as it is a smaller download. Is the file on a USB flash drive? Can you boot from a CD/DVD?
Edit: My mistake. I misread the file as EXT4 when in fact it is EX4. Please disregard the above.
Edit Edit; EX4 is a Metatrader file extension so I would have to assume you received the error because the file is corrupt. Right click the EX4 file, select open with and choose Metatrader to open the file. Does it open?
Edited by JohnC_21, 06 March 2015 - 09:28 AM.