Based on the details above, I'd recommend recording every transactions that occurred within the account, Sarah.
I'd recommend recording the deposit since you have received the check back. Here's how:
- Click the + New button in the upper-left corner and select Bank deposit.
- Select bank account where the amount is deposited and go to the Add funds to this deposit section.
- Select the affected expense account in the ACCOUNT column.
- Select the vendor under the RECEIVED FROM column.
- Enter the deposit amount and click Save and close.
You can use this link for reference: Record and make bank deposits in QuickBooks Online.
Also, you've mentioned that you've sent another check to the correct vendor. It'd be best if you record it as an Expense or Check, too. If the correct vendor has a bill that you want associate the check with, you can record it as bill payment instead.
Since you already reconciled the account, you can include the deposit and the check to the next reconciliation period. You just need to make sure these transactions are part of the bank statement.
I'd also recommend reaching out to your accountant regarding the reconciliation. They know what's best for you and your books.
Feel free to drop by again if you have additional queries about recording the transactions and reconciling the account. Have a great day!