Hi, welcome to TSF.
The partition table with the information about your files is gone - the files are still there.
Try this to repair the partition table:
Download the Windows version of
TestDisk.
Unzip the downloaded file to your C: drive and open C:\testdisk-6.8\win > double click "
testdisk_win" (the program doesn't have to be installed).
TestDisk runs in a command window, use the keyboard “arrows” to navigate, not the mouse.
A. At the first window select “No Log” and press the <Enter> key.
B. Select what drive to analyse, choose “Proceed” and <Enter>.
C. Select partition type – Intel if it’s a PC.
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 drive/partition to fix.
Then press <Enter>.
H. Select “Write” and press <Enter>.
I. Press “Y”.
J. Press <Enter> and close TestDisk. Reboot the computer.