I'm here to help you restore an inactive account in QuickBooks Online.
Perform the steps below to reactivate an account:
Go to the Gear icon at the top.
Select Chart of Accounts.
On the Action column, click the small gear icon.
Mark the Include inactive box.
Locate the account you want to make active again.
Select Make active.
When you make an account inactive, it doesn't automatically delete its transactions, so you can still access them through reports. However, if you have deleted all of them, you can recreate them manually by referring to the Audit Log.