I can’t link bank cause I accidentally unlinked

Welcome to the Community, @brownbeltbjj-icl,

I'd be glad to help you re-link your bank account. The existing data won't be affected if you have unlinked your bank. The ones you've previously categorized will then be kept, while the ones that need to be reviewed will be removed. This is because QuickBooks abruptly stops downloading new transactions. 

Allow me to guide you on how to reconnect your bank account.

Here's how:
 

1. Go to the Banking tab, and select Link account.
2. In the search field, enter the name of your bank, credit card, or credit union.
3. Select Continue. Then sign in to your bank with your user ID and password.
4. Follow the on-screen steps. This might include security checks your bank requires. It could take a few minutes to connect.
5. Select the accounts you want to connect, then select the account type ▼dropdown. Choose the account type that matches your chart of accounts in QuickBooks.

For detailed steps, please visit: Connect bank and credit card accounts to QuickBooks Online.

Your most recent transactions will be downloaded by the system automatically after reconnecting. Just review or match them to your existing entries in QuickBooks. 

I'll add articles that you can refer to for future reference if you want to categorize and reconcile your account in QBO:
 

• Categorize and match online bank transactions in QuickBooks Online.
• Reconcile an account in QuickBooks Online.
   

Should you need further assistance with your bank account, feel free to leave a reply. I'm here to help anytime. Have a good one.