External Harddrive Problem

Hello Everyone,

I have a 1Tb Fujitsusiemens external hard drive. recently when i turn it on, it keeps disconnecting and the auto run will be executed automatically every minute. I am sure there is no problem with the Power supply adapter Also I can not have access to some folders, It comes up with the message that this drive has not been formatted and asks if i want to Format it now.
I desperately ask for your help. I don't wanna loose the data on it.
Thanks