Do not use the command 
 'chkdsk /f /r c:' . 
  Use either 
chkdsk /f c: or 
chkdsk /r c:  Don't combine both those switches together.
  On modern disk drives, 
chkdsk /r c: implies the "/f" switch anyway, so it's an uneccessary duplication.  Check out this link to explain the switches:
Command Line Check Disk Options, Switches, Parameters
It would also be helpful to know the Make/Model of the hard drive you are attempting to run this command on.  And whether it's a 
HDD, SSHD, or 
SSD drive type.  Once you know that information you can run further manufacturer drive diagnostics by visiting this link:
Link Removed
When asking for help with this particular command which...