I accidently made bank account inactive and it made it zero. How do i reset it back to what it was before?

Hello, amkproducts.

I'll give some details about your situation and how we can get the transactions back.

When you disconnect an account, transactions that were not matched or categorised from the For review tab will be deleted. After you reconnect the account, QuickBooks automatically downloads your recent transactions.

If the transactions are older than 90 days, you won't be able to download them into QuickBooks again. However, you can manually import them using a CSV file downloaded from your bank's website.

Here's how:

1. Go to Transactions > Banking.
2. Click the Link account drop-down and select Upload from file. 
3. In the Bring your info into QuickBooks page, click the Browse and located the CSV file downloaded from your bank.
4. Click Next. 
5. From QuickBooks Account drop-down, choose the bank account where you want to import the transactions.
6. Hit Next. 
7. Map the fields and click Next. 
8. Select the transaction you want to import to avoid any duplicates.  
9. Click Next and then Let's go!.

You can open this guide for reference: Manually upload transactions into QuickBooks Online.

Once you have all the transactions back, you can categorise or match them. Here's an article for the steps: Categorise and match online bank transactions in QuickBooks Online.

Please let me know if you have any follow-up questions or other concerns. I'll be right here to help you out some more. Take care!