Help! Volume does not contain a recognized file system?

My external hard drive was working since i got it and i stored my work in it. today,I just plugged in my external harddrive will all my work!!!! to my computer and it said:

"Volume does not contain a recognized file system Please make sure that all required file system drivers are loaded and that the volume is not corrupt?

When I access it, it says i have to format it

WHAT CAN I DO!!??! CAN I RECOVER THE FILES?? THANK YOU!

What file system did you use? If nobody actually went to format the driver properly, you should be able to recover the partition table if you know exactly what you had on it ... I think.