My Book Essential 1.5TB USb 2.0 stopped working, no reason, wnats me to format it

Please HELP. Last week I came back from work and turn on my laptop and what to see:

New massage, My book was not recognisable, 0% usage, the drive has to be formated before it is used.

Till now it was working properly except some times it changes it drive letter fom G to H or opposite.

All my familly pictures on it. How to save them whithout to format the drive.

When checked the drive it says RAW, but it was working on NTFS??? Any help.

I tryed on other PC and Laptop the same massage. The drive has to be formated in order to use it.

How come it losess all the info by it self, when was working in the morning when I left to work and now no.

Please help any one 

It’s probably corrupt. Try TestDisk some have had luck with it. Never store important data on one drive internal or external no matter who makes it. One copy is not s backup.