HDD "C" partition not reconized

[geno112]

hp DV4 1275mx . the laptop stopped working , HDD error . i replaced the HDD and the machine is working . i tested the old HDD and it seems that the C partition has disappeared . the D partition is still there but the C is just gone . the capacity of the HDD is reduced to the D partition size . is there someway to fix this problem so i can recover the data on the disk and maybe use the HDD  ?

[PCdoc]

I would replace the hard disk, connect the old HDD to an external enclosure (USB). Use something like Ubuntu linux live cd to boot from the cd. And transfer all data to the new drive.