I've had my site live for about a week and it appears I've been hacked already

I need to change my password in phpmyadmin but I'm not sure what encryption is used. I tried a md5 encrypted password but it didn't work. Anything to do with the salt?
Any help would be much appreciated. Any security suggestions would be extremely welcomed too. My VPS should be pretty secure but obviously OC isn't yet.
Thanks
[--EDIT--]
Also tried a SHA1 encrypted password with no luck.