Lost icon Help please

My powerpoint program was working fine until I noticed about a week ago that
the icon was no longer the orange Microsoft picture that goes along with
Word, etc. It is now a little white square, and when I click on it, nothing
happens. I cannot pull up the program through my start menu, and a search of
my computer yielded nothing. The only way that I can access powerpoint right
now is to open an old one and go from there. It still works, I just have no
evidence that the program is on my system. Any suggestions?