I am unbale to mount my hard drive and i am getting following error message. i am new for ubuntu.

Error mounting /dev/sda1 at /media/krishan/8e7fa5f0-ceb5-44f7-8c67-ac16c6875d08: Command-line `mount -t "ext4" -o "uhelper=udisks2,nodev,nosuid" "/dev/sda1" "/media/krishan/8e7fa5f0-ceb5-44f7-8c67-ac16c6875d08"' exited with non-zero exit status 32: mount: wrong fs type, bad option, bad superblock on /dev/sda1,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so