There is no one hacking HL accounts or your IP addresses despite what a player trying to cause panic may be telling you. Their situation was caused by account sharing.

I'd like to take this time to remind you of the risks of sharing accounts with other players.
-When you share your password with another player, they can share it with anyone they want to.
-They can change your password and account information.
-They can access personal information you may have sent to someone else in owls.
-If the person logging into your account has four accounts, and logs into yours making it 5, if yours is the highest VE count on their IP it will be locked.
-If they are muted and get on your account to chat, your account will be muted.
-If they get banned and you are on their IP address, your account will be banned also.
-If they are a banned player, and log into your account to evade their ban, your account will be banned.

We will not help you recover a lost account due to sharing your information. This information should be kept private. I'd advise anyone who has been sharing accounts to change their passwords so they do not end up in the same situation as others before have.

Not everyone online is as trustworthy as you may think, they can tell you anything they want without you knowing if it is true or not. I would not trust anyone with your password.