I changed my bank account password and never updated quickbooks online, now i have 6 months of transactions missing? how can i bring them back?

Thanks for sharing your query here today, info2013. I can share detailed input to help you bring in online bank transactions in your file, so you can keep going in managing your business.

When you recently change your online banking credentials, you'll also have to update the bank information in your QuickBooks Online account. That said, you may click on the Edit sign-in info button to change the bank's password. Here's how:

1. Go to the Transactions menu and select Banking.
2. Choose the tile for the bank account. 
3. Click the Edit ✎ next to the bank name, and select Edit sign-in info.
4. Enter your updated bank password.
5. Hit Save and connect. 
6. Once you see a confirmation message, click I'm done, Let's go!

QuickBooks automatically downloads the latest available transactions. You can then categorize, match, or add them to the bank register. 

I'm also sharing this reference you can use to help ensure the accuracy of your books: Reconcile an account in QuickBooks Online.

I'll leave this thread available, so you can always reply below for any additional queries when managing online banking entries in your account. Let me know anytime, and I'll be around to help. Keep safe and have a good one!

@info2013 

You can use MT Online or one of the converter tools (e.g csv2qbo @ $60 one time license) as a workaround.

https://www.moneythumb.com/?ref=110