taxidriver

hi, i use this car as my taxi and the other day the drivers side window decided to pack up . it wont go up or down although all the others work ok, so idecided to buy a new switch unit and still no joy. i then stripped door card down to motor and cleaned wd40 etc all relevant wires , i also checked the wiring from the body to door , although not with a tester just to see if the was any broken wires, im still confused to see what is the cause?? is there seperate relays etc or something ?? any input would be a help