how can i recover a e1 system computer?

i have two computers the some one which im on is all working fine but the other one wont boot up it has lost some files on it windows root system 32 dll i beleive its i386 file .how do i download this file so i can fix the other one thats not working as both computers are both the same makes models. i dont no how you copy a file onto a cd or dvd so please can you explaine clearly to me urgent many thanks ri