Keyboard that dosent work

Hello, i have a problem..i just bought a used hp pavilion laptop..and the keyboard doesn't half work!what can i do? the only keys it will let you use are the numbers and the only letters it will let you use is ( C,G,H,L,M,T,V,X,Y,and Z)!!! and when i check the system it says that the keybored is working properly! what can i do to fix this problem! HELP ME PLEASE!