The process: I had a Windows 7 partition and an Ubuntu 11.04 partition on the same HDD. (35GB Windows 7, 400GB data, 15GB free for Linux). Windows 7 was installed first, then Ubuntu with GRUB loader.
In Windows 7, I removed the Ubuntu partition (carelessly, I must admit) to resize it, and reinstall a clean ubuntu 14.04.
In the process, it killed GRUB (and I don't remember on which partition it was installed). I was unable to boot Windows 7 anymore. So i managed to get a Windows 7 rescue shell and prompt some
bootrec /fixmbr and now i can boot normally on Windows 7.
Problem is : Windows 7 rescue disk and stuff cannot detect any Windows 7 installation on my HD.
bootrec /scanos or
/rebuildbcd tells me
0 Windows installation found!
Ubuntu 14.04.1 installer cannot find my Windows 7 installation / partition either! (And suggests a full erase disk & install, which is no good.)
How can I fix my Windows 7 boot? How do I reinstall GRUB? or Ubuntu, keeping my Windows 7 partitions?
I'm ok with installing a more aggressive Linux distro (but which one?) capable of detecting/cleaning my boot loaders and then reinstall Grub, and then I'll reinstall Ubuntu over it.