Let us know if you have a voltmeter. Or even a 12-volt lightbulb tester. You need this minimal level of test equipment to troubleshoot the problem yourself. If you have that we can talk you through a few checks, such as:
1) Must have 12-volts at the high-amp battery supply lead to the glow plug relay. (You have to pull the plastic cover off the glow plug relay to access this and other leads and plugs - the glow plug relay is on the drivers engine compartment fender.)
2) Must have 12-volts on both terminals of the high-amp fuse (a strip of metal) and the fuse must not look burned or melted.
3) After pulling the multi-pin connector on the glow plug relay that contains the wires that actually go to the glow plugs, you must get 12-volts on all six glow plug terminals immediately after the ignition is turned to ON. This normally might last for 30 seconds before the glow plug relay removes the voltage.
Come back and tell us your results. It's not possible for us to guess the problem, but we can help you test for it.