Ash here from the Shopify team. Welcome to the Shopify Community!
When an account is frozen, in order to re-activate it the account owner needs to log in and pay the outstanding balance on the account. Our Help Center also has some more information on reactivating a frozen account. Once the above actions are complete, the account should become fully active once again. It sounds like you're running into a problem while trying to make the payment, and I'm happy to help out with this.
What exactly seems to be the problem when trying to complete your payment? Are you receiving an error message of some sort? If so, please reply back here and send me a screenshot of the error.
This is an accepted solution.
I'm popping back in here to update the thread, as I see there have been a few users continuing to experience issues with re-activating a frozen account. If you're unable to reactivate your account for whatever reason and the steps previously posted didn't resolve your problem, then our team will need to take a closer look into your account to investigate what exactly is going wrong.
In order to look into an account, our team first needs to authenticate each user to ensure we're speaking with the stores respective account owner. At this time, authentication can only be completed via phone, chat or email. Please head over to our Help Center via this link, and either log in using your Shopify ID or choose to continue without logging in if you're unable to. Enter a topic into the search on the next page, and at the bottom of the results you'll find a button leading you to the current available support options. While there may be times where the phone option is not available due to business volume, our chat and email options should remain available 24/7.