|Install Active@ Partition Recovery and use the "Fix boot sector" option on that partition. Get it here: http://www.partition-recovery.com/|
"please help to get my data back"
You must never have your data on only one hard drive. You should always copy your data to another drive or to optical discs (CD/DVD). Hard drives can fail at any time (especially external hard drives) and when that happens there is no software that can get your data back. So you must always save your data on at least two drives, not just one.