do you still have coins ?
don't change the pvt key, ( you cant change). Create a ''NEW'' ETH adress, and send your coins the new wallet. its more safe,
BEAWARE: there a lot of fake myetherwallet.com like this;
myetlherwallet.com
myeltherwallet.com
they are fake and dont create and send your coins on these sites. Also your friend can be scammed too. don't enter Mew from advertisement link. there are tons of fake link.
JUST use original myetherwallet, stay calm but be fast
i dont know why people got easily fooled with Phishing sites
if you just bookmark the main site you wont have a problem inputting your private key
They are so lazy to look for the site where they input their private keys and some other fool kids get caught by that obvious site, And hacking is the payment for their negligence and surely they will be learn to be watchful for that happenings. And as advise just grab the legitimate site and we should always check on every site we wish to log our important details especially with our very own private keys.