From your description, it seems like the taskbar has simply increased in size due to an unintended drag/resize action. Follow the steps detailed below:
toolbar option button
Image Toolbar
No it is on the quick access toolbar.
Image Toolbar
If Your Talking About Microsoft Word Then, Because, You pressed a button that says "Hide Toolbar". Look for that again and press "Show Toolbar".
The home button is generally used to take user to their default page. It depends on what toolbar you are using.
toolbar option button
The undo button.
spell check
spell check
Open the View menu and then Toolbars and then the Control Toolbox toolbar. From that you can draw a Command button. A button can also be drawn if you use the Forms toolbar.
Option button