How to fix western digital hard disk that can't be read

My laptop suddenly couldn't load windows from my internal western digital hard drive. I replaced it with a new hard drive and put old wd hard drive as external to try to recover its contents. Windows detected it as drive e but couldn't read its contents. Tried recovery programs such as GETDATABACK and TESTDISK. The problem is these couldnt even detect the old wd hard drive. What can i do? Please help. I really need those files.