just follow the dead player recovery guide. there is step when ur window show ur mp4 as unknown device. u right click on it go to properties and update driver, and show all devices go next and then click on have disk and go to mycompeter/C and then windows, and open afduUpdate.info, here is the link which will show u these steps with pictures,
http://www.mympxplayer.org/dead-play...recovery+guide