听起来您删除了grub配置。
您需要再次安装grub。根据您安装的grub,
给自己一个ubuntu或类似的启动盘,然后
使用以下命令来识别您的磁盘描述符
sudo fdisk -l
然后:
sudo apt-get install grub
grub-install /dev/<disk name>
例:
user@ubuntu:~$ sudo fdisk -l
Disk /dev/sda: 300.1 GB, 300069052416 bytes
255 heads, 63 sectors/track, 36481 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: 0x045a0459
Device Boot Start End Blocks Id System
/dev/sda1 * 1 31871 256003776 7 HPFS/NTFS
/dev/sda2 31872 36480 37021730+ 5 Extended
/dev/sda5 36290 36480 1534176 82 Linux swap / Solaris
/dev/sda6 31872 36289 35487522 83 Linux
Partition table entries are not in disk order
user@ubuntu:~$ sudo grub-install /dev/sda