hard drive formatted while Linux setup, lost partitions

I have installed Ubunto 14.04 on sda1. but after the installation finished, all the partitions are gone . I have important data on sda5 , and when I run the following command : sudo fdisk -l in the terminal the following appears :

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000cf11e

    Device Boot      Start         End      Blocks   Id  System
 /dev/sda1   *        2048      499711      248832   83  Linux
 /dev/sda2          501758   976771071   488134657    5  Extended
 Partition 2 does not start on physical sector boundary. 
 /dev/sda5          501760   976771071   488134656   8e  Linux LVM

 Disk /dev/mapper/ubuntu--vg-root: 495.6 GB, 495594766336 bytes 255
 heads, 63 sectors/track, 60252 cylinders, total 967958528 sectors
 Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical):
 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096
 bytes Disk identifier: 0x00000000

 Disk /dev/mapper/ubuntu--vg-root doesn't contain a valid partition
 table

 Disk /dev/mapper/ubuntu--vg-swap_1: 4202 MB, 4202692608 bytes 255
 heads, 63 sectors/track, 510 cylinders, total 8208384 sectors Units =
 sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512
 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes
 Disk identifier: 0x00000000

 Disk /dev/mapper/ubuntu--vg-swap_1 doesn't contain a valid partition
 table

The total size of the hard drive is 5oo GB