If your account was wrongly accessed by another individual you may want to get in contact with Mojang and ask them for any information they may have. We aren't a policing force for protecting Minecraft accounts, that is a job for both yourself and Mojang.
I would suggest you look into improving your password strength as "hacking" isn't likely to have taken place, but more likely cracking or phishing.
Sorry but there isn't much we can do to help you, the security of your Minecraft account is nothing to do with us.