Laptop keyboar'd problems

Hello,
ive obviously pressed a sequence on my laptop keyboard,now when i press the u key it prints the no 4 and i=5,o=6,j=1,k=2,l=3..if i hold down the Fn key in the bottom left corner everything prints normally, how can i change it back to normall...ie not having to hold down the Fn key to get a K to print as a K and not a 2.