logitech wireless keyboard typing problem... plz help..its little urgent

hi,
i have a logitech mk320 wireless usb keyboard and for past 1 week,it type wrong.
all other letters are ok but when i type "c", it functions as home button and when i press "backspace", it displays "x". i could nt use ms office bcoz of this.

i removed reciever from usb and reinserted in another socket, changed to new batteries, restarted pc... but of no use.
plz help at the earliest