Space bar when pressed gives me a number 4

Question

was on my yahoo msn dunno wot i pressed 4now my spacebar is gi;vin me 4s if i press F get pf the caps lock when pressed beeps th0e 4letter gi;ves me 0r i;ve had to delete letters/numbers so u can read this 0r there wud be 4s before e;ve0rything an jus noticed som keys like 4;v gi;ving me apostrophes