Hi Aminat, 

Welcome to the QuickBooks Community! It’s great to see you here, and thank you for taking the time to share your question. I understand how important your client data is to the smooth operation of your QuickBooks account, so I’m here to walk you through the steps to quickly restore your client and their information.

In QuickBooks Online, when a clients that are deleted, they are marked as inactive rather that being permanently removed from the system. This feature allows you to reactivate them easily and bring them back to your active client list whenever needed.

Here’s how you can do that:

1. Go to the Customer Hub section and click on the Customers tab. 
2. At the top of the customer list, click the small Gear icon above the Action column header. 
3. Next, select the Include inactive checkbox in the dropdown menu. This will show you both active and inactive clients. Look for clients marked as "deleted" next to their name.
   
4. Find the client you’d like to restore from the list.
5. In the Action column next to their name, click Make active to reactivate them.
   

On the top of that, you can use the Customer Contact List report. This will display all customers including deleted/inactive ones, making it easier to identify which customer needs to be restored. Under Filter, select the Deleted.

Here's more information on how to add, delete, merge, and restore a customer.

Once you’ve completed these steps, your client will be restored to your active list, and their data will be accessible again. If you run into any trouble or have additional questions as you go through this process, don’t hesitate to reach out. I’ll be here every step of the way to help.