This is not the answer you're looking for, but you'll need to pay some money to fix this.
You do not want to chkdsk this drive.
Since the partition (volume) is not accessible, you need a program to look at the drive and recover the partition. My brother has a Mac and put his external drive into his GF's PC and it formatted it (Windows format = delete partition table) so he had to find a software package to read the partitions and restore them.
is ~$40 but that's what he used and was able to recover all of his stuff.
To OS-Wiz's point, you need to backup your important data. My important docs exist in three locations (One External Drive, One Internal Drive, DVD). DVD's have a lifespan of 100 years, so they will survive many harddrive failures. Put your stuff onto DVD's and store them in a safe place.
Humans are the only creatures that won't live up to the their potential. Give everything your all. When you die, die on E.
So I ask you, what do you intend to do now?