That's a grub-related topic, not a bt-related one.
Moreover, google offers plenty of useful and precise answers about "how to make a partition bootable" or "I reinstalled windows and since I don't even begin to try to understand how it worked, I think I f***ed up my computer"...
I don't complain because I think your question is stupid. It's certainly not... I complain because your are far too lazy to search the web and try things by yourself.
You're a "beginner" (since that's the "beginners forum"), try not to stay like this your entire life.