See if TestDisk can fix it:
Download the Windows version of
TestDisk.
Unzip the downloaded file to your C: drive.
Open
C:\testdisk-6.8\win > double click the "
testdisk_win" icon.
Each of the steps (A, B, C etc) below corresponds to a new TestDisk window.
Use the keyboard's arrow keys to navigate.
A. At the first window, select
No Log and press the <
Enter> key.
B. Select which drive to analyse, choose
Proceed and <
Enter>.
C. Select partition type Intel if its a PC then <
Enter>.
D. Select
Analyse then <
Enter>. The drive/partition will be analysed.
E. Select
Proceed at the next screen, then <
Enter>.
F. Press
Y if the partitions were created under
Vista
N if not.
G. TestDisk should say
Structure OK. Choose the partition to fix. Then press <
Enter>.
H. Select
Write and press <
Enter>.
I. Press
Y.
J. Press <
Enter>.
Close TestDisk and reboot the computer.