Trouble mounting external harddrive

This external harddrive worked early this morning. Here's what I get when trying to mount it now:

"wrong fs type, bad option, bad superblock on /dev/sda1, missing codepage or helper program, or other error".

I've looked on line for clues but I'm not making much progress. I'm confident that my drive is named /dev/sda1 but that's the extent of my terminal knowledge. Appreciate any help.