Why is my LED not blinking?

[Archangel]

I have even changed the breadboard. What else can I do?

Try a different programmer software, and or a different programmer.
I use ICPROG available on internet free, with a JDM clone programmer I bought off ebay from a seller in Bulgaria, cost 18 bucks and works always.
http://www.ic-prog.com/index1.htm
edit:
you said you have used stamps for years, which programmer did you use on them, is the one you are using now? Are you using a bootloader to load your PIC? And I am just covering the bases here and not trying to offend, you are loading the HEX file and not one of the others, correct? Last thing, verify MCLR pin is at or near 5v+ when operating, do not attach any load to it though. I had once hooked an LED to MCLR so as to observe and verify reset switch operation and PIC would not work.