Hi, why you want to recover your university exam data. If you previously backup your Mac using Time Machine/online backup storage, then just restore it and regain access to lost or deleted files. However, if you have done some laziness and do not have a proper backup available, then there are no other options left other than using a data recovery software for Mac. You can use Stellar Phoenix Mac Data Recovery Application Program to retrieve all the deleted files back to the hard drive. This software for data recovery supports more than 500+ file types for data retrieval. Also, data rescue is a good software but its features are limited like Time Machine recovery, RAW recovery, BootCamp partition recovery.
Could you provide some details; for instance i) Is your hard drive appearing in Disk Utility? ii) Have you checked the SMART using WD or Disk Utility? iii) You didn’t mention any instances of physical damages i.e. clicking, buzzing sound hence I consider your hard drive logically damaged Solution i) If your external drive is backed up then erase the utility either through Disk utility or with Terminal ii) You can also create image of your external hard drive and reformat the hard drive iii) If all fails, then the last bet is data recovery. Try Macintosh data recovery http://www.macintosh-data-recovery.com/ to recover data from failed external hard drive
Before you go in the terminal way, you must take the complete data backup of your Mac since a single wrong command line will invite new trouble and your complete Macintosh hard drive can now be unrecognized. Other way round will be using a partition manager utility by creating a bootable USB and then resizing / creating / deleting partitions. You may look at below mentioned apps partitioning your Mac: 1) Stellar Partition Manager 2) iPartiton