Usually (but not always) the washers are protected by the same fuse as the wipers, so if the wipers work I would presume the fuse has not blown. Can you hear the washer pump motor going? If so the jets may be blocked. If not you need to check for a power supply at the motor when the switch is operated. Does the car have a rear wash/wipe? And does the rear washer have a seperate bottle and motor or does one motor do both? Does the rear washer work if it's operated from the same motor. Answers to these questions should narrow your fault finding right down......