missing device drivers

Hi
I would really appreciate some help. I was cleaning up
my computer (windows xp home)erasing old and unused
files, I must have erased an important component due to
the fact that I cannot install anyhing for it states that
there is not a windows installer I cannot access the
internet, no modem driver, I cannot system resotre for
there is no restore point, I am at the point of crying!!!
Please Help!
..