Try Menu / Show All. You may have inadvertently hidden it. Or if you have folders on your home screen, look in them to see if you inadvertently moved it to a folder. Finally, reset the device, Alt-R.Shft-Del.
Which suggestion worked? And welcome to the forums! For good, general information, be sure to check out the Getting Started Guide and the BlackBerry 101 Lecture Series under the Newbies tab at the top of the page.