Most of the time, someone has resized the taskbar so that it can no longer be seen. If you look closely at the bottom of the screen, you might see a thin grey line. That's the taskbar. Move your mouse down to the bottom of the screen. When the cursor changes to an arrow pointing up and down, click and hold the left mouse button. Then slowly drag the mouse upwards. You should see a line moving up the screen. When the line has moved up from the bottom of the screen, release the mouse button and your taskbar should be there.