Restore grub2 after Windows installation

To run a command as administrator (user "root"), use "sudo ".
See "man sudo_root" for details.

ubuntu@ubuntu:~$ sudo fdisk -l

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x14311431

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1       29089   233657361    7  HPFS/NTFS
/dev/sda2           29090       32129    24418800   83  Linux
/dev/sda3           60304       60801     4000185   82  Linux swap / Solaris
/dev/sda4           32130       60303   226307655   83  Linux

Partition table entries are not in disk order

ubuntu@ubuntu:~$ sudo mount /dev/sda2 /mnt
ubuntu@ubuntu:~$ sudo grub-install --root-directory=/mnt/ /dev/sda

Installation finished. No error reported.