Scroll Bar missing in MS Excel

Sometimes the bottom scroll bar and worksheet tabs "disappear." How do I get them back? I am sure this is a simple question but can't find it in my reference book. Thank you...

see if they've been hidden :

tools
options
view

horizontal scrollbar = checked ?
sheet tabs = checked ?

(taken from : http://www.mrexcel.com/forum/showthread.php?t=7201)