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
There are lots of pishing site and there been a thousands who are already been victims of it.
All you need to do to avoid this pishers is that go to the right adress and bookmark it so there's no way for you to go on other site like the MEW wannabe.
Also keep your private key safe from anyone and everyone because you and only you are the one responsible for your own security.