have you opened the chart of accounts from the gear menu, and then clicked use register from the selection arrow on the bank account line?

If you are trying to get to it from the dashboard, intuit has a known problem with that widget

Resolution for 'bank account line issue: 'ANYONE KNOW WHERE BANK REGISTER WENT? IT SEEMS THEY WANT TO MAKE YOU TO CONNECT YOUR BANK ACCOUNT. CAN’T GET TO IT.' available: Yes.

The bank account line issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the bank account line issue yourself by looking for a resolution described in the article. If it is a complex bank account line issue or you are unable to solve the issue, you may contact us by clicking here or by using other bank account line support options.

For more information about resolving issues related to bank account line in Quickbooks/QBO or to get support for the issue 'ANYONE KNOW WHERE BANK REGISTER WENT? IT SEEMS THEY WANT TO MAKE YOU TO CONNECT YOUR BANK ACCOUNT. CAN’T GET TO IT.', click the link below: