Disk utility cannot mount or unmount WD external hard drive?

Hello all,

The other day, I went to play a movie from my 2 tb WD external hard drive, but it wouldn't mount. I could not and have not found anyway to get it to, and sik utility cannot repair the disk either, I get an error. So instead I thought I would reformat the drive, and partion it, as my IT knowledge has grown. However, disk utility cannot do either as it says that it could not unmount the drive...that it also cannot mount. I found an article that said to disable spotlight as it was using a file and wouldnt let go (sudo -a -i off) which went fine untill it asked for my password, I do not have one. So I presssed enter and it said wrong password, so i entered my last known password, and now I am locked out (

sudo -a -i off

usage: sudo -h | -K | -k | -L | -V

usage: sudo -v [-AknS] [-g groupname|#gid] [-p prompt] [-u user name|#uid]

usage: sudo -l[l] [-AknS] [-g groupname|#gid] [-p prompt] [-U user name] [-u

user name|#uid] [-g groupname|#gid] [command]

usage: sudo [-AbEHknPS] [-C fd] [-g groupname|#gid] [-p prompt] [-u user

name|#uid] [-g groupname|#gid] [VAR=value] [-i|-s] [<command>]

usage: sudo -e [-AknS] [-C fd] [-g groupname|#gid] [-p prompt] [-u user

name|#uid] file ...)

any help would be appreciated, and I apoligze if I have done anything wrong, this is my first time asking for help on a forum ahah.

thanks in advance.

i can provide any other details if i have missed any