If the tool bar is gone - there isn't any START button or clock or anything at the bottom of your screen.

First try and move your cursor (the arrow) all the way to the bottom of the screen. If the toolbar is just hidden - it should pop up and be useable.

If that doesn't work hit the key on your keyboard that looks like a window. That should bring up the START menu

1. Click SETTINGS - TASKBAR & START MENU
2. Click LOCK TASKBAR
3. Click KEEP THE TASKBAR ON TOP OF OTHER WINDOWS
4. Click APPLY then OK

This gives you choices - AUTO HIDE - if you want the task bar to hide untill you put the cursor all the way down to the bottom of the screen. SHOW CLOCK - check or uncheck depending on if you want the clock or not.

Then click OK for it to take effect