As the tittle states his email account got hacked,and trough it many other accounts such as steam ,origin and who knows what else,also the intruder is mocking him sending emails to himself,what can he do until the local or government authorities take over the case,the country is Croatia and the mail is from out news site called Net.hr,the possibility of a virus/malware etc. is unknown various antivirus programs have been used and also a reformat on one machine has been done in order to possibly sort out this case.
I doubt the local authorities can do anything even if they did step in. Just don't click on random emails from people or website you don't know. Reformatting a machine wont get your email account back.
I am fully aware it was his idiocy that he reformated the question is now what can he if he can do anything to perhaps get his email and or accounts back or possibly shut down his email to prevent any further damage,and my thoughts are that his ip somehow leaked trough steam and the hacker got hold of further information to continue damaging him
Unfortunately the mail has been lost but other accounts have been redeemed,thank you all for the suggestions but the system of this freemail was so bad there was no other way but to disregard it and ultimately deleting it.