External Hard drive says it needs to be formatted

I have been using my External hard drive for about six months with no problem. The other day when I tried to retrieve the hundred of pictures on the device, in my computer it is no longer calling it the proper name. When I clicked on the H drive to open it, it said it needs to be formatted - which I did when I initially set it up. Like I said, it has hundreds of pictures on it. How do I access this drive again without reformatting and losing all of my pictures?

I am having the same issue, occasionally. Otherwise it  powers up and is there but is EXTREMELY slow! It has been working fine for the past six months. Help! Thanks!!

A data recovery software like Recuva or Test Disk should help