there are two types of drive failure: logical and mechanical.
if you're suffering from logical drive failure you could recover files with recovery software (such as recovermyfiles). it'll cost $$ and take time.
if you're suffering from mechanical failure (typically identified by the drive making a noticable clicking noise) then you're probably SOL. you could take it to recovery specialists, but that'll cost $$$$$$ and there's no guarantee of anything being recovered.
if and after you recover what you can, do two things: 1) STOP using that drive 2) START backing up your data!