laptop keyboard

hi, i have a dell inspiron 3700 laptop. some of the keys have stopped working on the keyboard. i took out the keyboard and when i put it back in the keys worked fine , but other keys stopped working. does any one know can this be fixed , or will i have to replace the keyboard. if the keyboard needs replacing what other keyboards are compatable with the 3700. i would be greatful for some help on this. thank you...