There are two levels of "locked" that can apply to your online account with Verizon Wireless.
If you have unsuccessfully attempted to log in several times, you will be blocked from trying again for several hours. I believe this lasts for three hours, but I'm not certain. If this happens, you will need to either wait it out or try to reset your Online Password. If you call Customer Service at this step, they will only be able to walk you through resetting the password, which is something you really should be able to do on your own.
Now, if you have unsuccessfully attempted to reset the Online Password so many times, you will be given a message stating your account has been locked and at this point you WILL need to contact customer service to have the account unlocked. You will still have to verify account information at this point, but your Customer Service Rep can assist in "secondary verification" if you need it. As long as you can verify the account, they will lift the second-tier block and walk you through resetting the Online Password as before.
In order to reset the Online Password, you will need three of four things: Your five-digit billing zip code as it appears on your bill and either the last four digits of the account holder's SSN (or tax ID for business accounts) or the one-to-five digit Billing Password (this is different from the Online Password) if one has been established. Once that is clear, you will need to either be able to answer the Secret Question, if established, or have the phone number you entered available to receive a temporary Online Password through text.