I am on a school computer and have lost the taskbar on the desktop. How do I get it back?

move the cursor down to where the task bar should be, untill you see a double pointed arrow , press left mouse button and drag up

.... or, ask your Teacher

I was doing routine maintenance on all the school machines, and the bar got away.I tried grabbing the bar with the two headed arrow, but couldnt get it to move.

Right Click down there and make sure that Lock The Taskbar is UNchecked.

well, that probably already is true. I had moved it off the top to the right side, and was trying to get it down to the bottem and it got away from me. Have been right and left clicking forever to no avail. Will check on it next week when I get back in there. Sometimes it misbehaves, but later cleans up its act.