It is very unlikely that the LED is damaged. They are not made of glass and they are almost indestructible by mechanical shock. More than likely there is a bad connection. The problem may be at the connections to the switch, the switch itself, or the two connections to the battery terminals. But the problem may be inside of the plastic housing that holds the LED which is really non serviceable. you can test the assembly by connecting it directly to the battery terminals with clip leads and shorting the two metal strips that contact the switch with an additional clip lead. If it does not light, reverse the leads on the battery terminal. If it still does not light, the problem is a bad connection on the inside of the plastic housing. If it does light then there is a bad connection to the switch or battery or the switch is broken.
I have bought 12 of these so far as gifts (kept 2) and have had zero failures. You may want to buy a new one. They are worth it. I modified all mine for longer run time (added resistor, 300 hours) so mine have had a lot of use. One of them is on battery number 3 and after nearly 1000 hours the only problem is the rubber cover on the switch has torn.
Hope this helps.