"Start" bar help? On computer?

I'm not sure what the correct name of this is, but the little bar on the bottom of my screen that has the "Start" menu on, and the time on it, it's gone. LIke, there isn't that line/bar thing anymore. It's just gone. Any way to have it reappear on my screen? I need to open a file, and I can't because there isn't a start menu on!