I'm Miles from the Social Care team at Shopify.
If your account is locked, then it's likely you've received an email from our accounts team with some instructions on how you can have the lock removed. This will generally go to the email address listed on the account and will contain contact details for the team for you to directly contact. If you reply to that email, please allow 24-48 hours for a response, otherwise you may be provided with a direct phone number for the Advisor dealing with your account. Keep in mind, certain teams are only available during normal business hours, so you may not be able to reach them until tomorrow.
If you require urgent help, it's always best to contact Shopify Support directly.