In some cases you may find search components are not online so you must delete and recreate the search service application. Below are the steps to do that.
Go to SharePoint Central Admin.
Manage Service Application in blue under Application Management.
Click on the Search Service Application in blue so that it is highlighted.
Click the delete button in the top menu.
- You will get the below warning. Click the "delete data" checkbox and click "OK."
- Go back to the main sharepoint screen.
- Click Configuration Wizards.
- Click Launch the Farm Configuration Wizard.
- Click Start the Wizard.
- On the next screen ensure the correct search user is chosen(i.e. the user used to setup search server).
- Click skip on the next screen.
- Click Finish on the next screen.
- Follow the steps in the below KB to confirm the search service application is setup correctly.
Sharepoint service health