Toshiba L305 with Vista

Hi,
My 'BACKSPACE' won't work so I highlight letters, then 'DEL' button.
Upon typing:
't' it automatically types 'gt'
'l' it automatically types '.36'
'i' it automatically types ',ki'
's' it automatically types 'sw2'
'w' it automatically types 'sw2' and on...........
Numbers are fine and show what I type.

I would appreciate any help........
TNX

I had to use my friend's computer to type these!!!