bank reconciliation

You'll need to recreate the deleted transactions and manually reconcile them to correct the beginning balance, Ranchu.

Here's how to manually reconcile the created transactions:

1. Go to the Gear icon, then Chart of accounts.
2. Locate the account that contains the transactions and click Account history.
3. Find the transaction and select it to expand.
4. In the checkmark column, click the box until you see an R.
5. Hit Save.
   

For more information, check out this article: Fix issues for accounts you've reconciled in the past in QuickBooks Online.

Once done, you can now continue reconciling your account.

Feel free to return to this thread if you have more concerns about reconciliation.