Your Bcd file crash error is caused by windows update, startup repair or hacking your pc.Windows 7 and XP do not have these problems because they have a file name: bcd.backup.0001 for repairing the bcd file but in windows 8 and 8.1 there is no file of bcd.backup.0001 for repair.so get bcd file using another pc AND save it in your usb from :https://www.dropbox.com/s/gkv6lrgkpcmatge/BCD?dl=0

for windows 8 and 8.1 use 

INTRUCTIONS:
you must have a windows setup boot cd
boot your windows CD
select your windows language 
click next
click repair your computer
select the windows 
click next
click command prompt
first you have to know what is your USB location like (H:)

type:

c:
del c:\boot\bcd
copy H:\bcd C:\boot\
then restart your computer run windows 8 or 8.1 operating system it will run with no error