I’ve been using my D3100 for awhile now. Today I took a few pictures using the flash and everything worked fine. After that I spent some time exploring menu set-up options and played with a few settings. Since then I have observed that my flash isn’t working. It pops-up properly under low light but doesn't produce any light. I went to menu setup and reset all the options but still flash doesn’t flash at all. However, it pops up properly. Any suggestion on if I need to do anything or is going to the service center the only option now?
Sorry mate, looks likes you'll have to take it in. Try calling your near by Nikon service centre, and getting someone at the service desk, they usually can give you a an idea of if you need to bring it in.
If it isn't working after resetting, or not even firing in dark areas under full auto mode it probably needs repair :(
Here's a video that shows what hardware problems could prevent it. I know it's a D40, but same principal. I don't suggest you open it up, got zapped plenty of times :)