Recently i was installing ubuntu 12.04 on my system. There were 4 partitions on my system and i selected one of the four partition for the installation and chose the option of re sizing the partition. Initially my partition was of size 100+GB and i created another partition out of it of size 15GB (EXT4). Now the moment i changed this partition structure my original partition got lost along with its data and i am left with 50GB partition and 50GB unallocated free space.

Now the data that i have lost is meant a lot to me and i want to recover that data. So is there any way i can recover it ? And i haven't checked "format" option while resizing the partition.

Thanks in advance.