555 timer ciruit errors
I can't see from your picture: does the yellow wire go to pin 8 and the white wire go to pin 7?

The easiest way to troubleshoot this is to use your LED as a test light.

Disconnect the lead that goes from pin 3 and connect it to your +V rail.  Does the LED light?

Now take that lead and check pins 4 &amp; 8.  Does the LED light?