If a true crash, you will need to supply the drive to a computer service company and have them try to recover your data. In many cases, a major portion of the stored information may be recovered. However, unfortunately, in some cases, a majority, if not all, data may be lost.
Most external hard drives have a piece inside that looks like any normal internal hard drive. These can be removed and directly installed in a full sized computer. The drive can then be read by the tower computer provided the drive itself is not broken. If it is broken it will need to be shipped to a data recovery house.
You can try running a command from the command prompt called chkdsk. This will check the disk and attempt to fix bad sectors on it. If that fails, contact the manufacturer.
you can use software recovery tools this software will recover your file but the recover file wouldnt have any extension in it.
or using hardware but i wouldnt suggest doing it your self if the software doesnt work than just leave it to the pro.