Welcome to the Community, @amy-homesfirst-o.

Let me chime in and provide information for you to restore your deleted vendor in QuickBooks Online (QBO).

As what @Just_me said, to restore your customer or vendor you'll have to :

1. Go to Expenses, then Vendors, or go to Sales, then Customers.
2. Select the Settings from inside Vendor/Customer screen, and select Include inactive to show all inactive list items.
3. After that, Select the checkbox by the customer/vendor name
4. Then Under the Action column, select Make active.

Additionally, If ever you want to restore your deleted product or service items, here's how:

1. Select Settings ⚙, then Products & services.
2. Select the Filter icon.
3. From the Status dropdown menu, select Inactive, then Apply.
4. Locate the product or service you want to make active.
5. Select Make active.

For more detailed information, refer to this article: Edit, delete, and restore list elements in QuickBooks Online.

I'll also add this article to guide you on how to enter a prior balance for a customer that owes you money or a vendor you need to pay: Manage outstanding balances for customers and vendors in QBO.

I'll always be here, ready to back you up if you have any further questions about restoring a deleted vendor or other QBO-related concerns. Please let us know any time in the thread. Keep safe!