If you use the "fixmbr" command from the Recovery Console there should be no danger of data loss. The only circumstances under which that might arise would be if the command altered the Partition Table - it will only do that if the Partition Table is corrupt, and then it will warn you before making any changes.
Having said that, it's never wise to say "never" as far as computers are concerned. The only safe policy is to ensure that, at all times, you have an up-to-date backup of any important material.
In windows manage , my external HDD shows as not initialized, if i intialized it , will i loss my data? if yes , then what is the way to get data back?
My HDD has 3 partitions, but in manage it is not showing any partition and only shows one unallocated space with message to initialize HDD .
Yes - initializing the HDD will, essentially, lose all data. There are utilities, and data recovery specialists, that can recover such data. Try Googling "recover partition" or similar phrases for a few suggestions.
Just did what you did "initializing the wrong HDD" and was gutted, thinking i would have to recover every sector, but luckily i found this A* App that just detected and recovered the deleted partition in minutes. Best part apart from returning my data back to normal is that it is also FREE!!!!!!!!
I just thought i would post this as im sure it might help some one out again!