will my data be gone during this process?
Depends on what you mean by your data.
If your data means:
1. Customized Windows settings
2. Your files
3. Your installed programs
Number 2 & 3 won't be lost, unless something goes wrong with
the repair process. I can't recall for Number 1.
If you have a live CD such as Linux or UBCD4Win, try booting up
to it, copy all your personal files to a thumbdrive or external
hard disk before performing a repair.
Otherwise, if the repair process goes wrong, you will eventually
lose everything.