Beginner! :)

[omckellar]

I lost all of the icons on the left side of my Adobe Illustrator . . .  Where did they go?  How do I get them back???

[Myra Ferguson]

Did you hit the F key? Hitting F toggles through various view. If you tap F again, you'll eventually get back to the original view.

If you accidentally undocked or closed it, you can go to upper right where the workspace is set to Essentials. Open the drop down menu and go to Reset Essentials.

[Monika Gause]

If it's not the F key, try the TAB key.

And please read the documentation:

Illustrator workspace basics