How to Open/Add tab group to right panel.

[#1]

I was working with Illustrator and I accedently closed the gradient tab on the right (Close Tab), and I'm trying to find a way to reopen it. It was set to "Essentials Classic."

Here's the gradient icon that's missing: 

It does not appear on the right panel: 

Any help is much apprecitated.

[#2]

I was working with Illustrator and I accedently closed the gradient tab on the right (Close Tab), and I'm trying to find a way to reopen it. It was set to "Essentials Classic."

Here's the gradient icon that's missing: 

It does not appear on the right panel: 

Any help is much apprecitated.

[#3 · Accepted solution]

Choose:  Windows > Gradient and drag it back?