My external Hard drive has lost all data and says it is unformatted…

Since last week my external hard drive says that it needs formatting – it says there are 0bytes used and 0 bytes free and all my data is lost.. is there any way of recovering the data?
ive tried pc inspector file recovery but it isnt seeing any logical drive on my external to recover the files from.
would it help if i format the drive and THEN try to recover the data?

Anyone know what is the best freeware tool to help me?
any help is incredibly appreciated as it has an awful lot of data on it :/