How can I make inactive vendor to active again?

Hello there, @CuriousKeeper.

You've got me here to provide some insights on what will happen to your data if you make a vendor inactive or active again in QuickBooks Online.

Making the vendor inactive won't delete their information. You can still view their previous transactions and activity in reports, but their name will show as Deleted.

Moreover, any open transaction like PO for the inactive vendor can no longer be processed. You have to make the vendor active again to generate the entry successfully.

Here's how to make a vendor inactive:

1. Select Expenses.
2. Select on Vendors.
3. Click on Make inactive in the drop-down menu beside the vendor you want to make inactive.

To make your vendor active again:

1. Go to the Expenses menu.
2. Select the Vendors tab.
3. Make sure to select the Include inactive option from the Settings icon above the Vendors List table.
4. Locate the name of the vendor(s) you want to activate.
5. Click the Make active option under the Action column.

To give you more details about  inactivating or restoring transactions in QuickBooks Online, you can always check out this link: How to edit, delete, and restore list elements.

Please know that you're always welcome to comment below if you have other concerns or follow-up inquiries about managing vendor accounts and transactions in QBO. I'm just around to help. Take care.