Recovering the data off of a computer hard disk can be a tricky and complex job, so rather than make any recommendations on how to go about this, we would always advise to seek professional help (such as ourselves) instead of asking your friend (who may know a bit about computers), as the friend might make the problem worse.
In this case, the information was stored on a Samsung 1Tb hard drive, and in order to restore the data it was necessary to get a system to read the structure of the hard drive, as the information was corrupted, even though the hard drive hardware was fundamentally in good shape. Once the data was transferred onto anohter drive it had to be scanned/repaired and although there were some damaged files, pretty well all of the files were in tact upon recovery.
Recovering files, such as your photos, Videos, documents etc, can be a time consuming task and hence expensive to carry out. Data recovery charges typically run at around €250, and in many cases can exceed €1000 in total depending on the nature of the damaged data, and the processes involved in it's recovery. Hence if you are storing valuable family photos and videos for example, it is important to make sure that they are backed up, otherwise they may be lost forever, in the event of a hard disk failure (which does happen, but thankfully we seem to recover over 90% of what we work on).