I installed Ubuntu 12.04 on my laptop and chose the option "Erase disk and install Ubuntu" from liveUSB without any backup. When I realized that this would format my whole HDD, I immediately unplugged the usb and turn off my laptop. However, it seems that my whole HDD had been formatted: I have 4 partitions before but there's only 1 partition formatted in ext4 now with the size equal the HDD's size.
Is there anyway I can get my data back? I believe that my data is still there on the disk. I've searched for a while and tried using Testdisk and parted but no luck: Testdisk cannot find any partition even after trying "Deeper Search"