Q&A for How to Alter the Size of Your Windows Desktop Taskbar

Go right to the edge of the taskbar with your mouse. Your mouse should change icons to a double-sided arrow. Now, just click and drag the taskbar to as tall as you want.

Place your mouse just over the top edge of the taskbar and the cursor will turn into a two-sided arrow. Click and drag the bar down. If your taskbar is already at the default (smallest) size, right click on it, click settings, and toggle the setting called "Use smaller taskbar buttons". This will reduce the size of your taskbar icons, reducing the size of the taskbar along with them.

Taskbar and start menu properties > Taskbar > Unclick the "Use small icon".

If your taskbar is visible, i.e., not hidden in Settings, then the start button should always be visible. One of the main reasons it can sometimes disappear is that your screen resolution is set to something not supported by your equipment. Go to Display Settings and choose a different resolution than that which you are now using. Try something low to start with, like 1028 x 768, and see if that rectifies the issue.