Runescape Account: Hacked? Nothing you can do?

Hey i feel you, i havent been on in like 4 or 5 years now, and i just started to check it out again for like a week. nothing was gone but i decided to give my account to my little cousin since i wsnt using it anymore. not even a few days later she called me telling me she doesnt know what happened, i logged in (same password) and everything was gone, i had lost over 20 mil of stuff. it didnt effect me but i felt bad for my little cousin that she just started playing and now she just got screwed over. is there anyway i can get the stuff back that she lost, cause i want to get them back for her