7805 5v Regulator outputting 5.8v? TTL chip not functioning correctly? LED + TTL chips?
Do you know that the horizontal strips of a breadboard are all connected together (except sometimes in the middle)? To me this looks like you have shorted the input to the output of the 7805. (Or maybe the output to te ground, my view is blocked by the capacitor.)



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OK, next step. You are using a plain old 7400, no LS or HC or any other letters between the 74 and 00? That old chip requires 5V. If you used it at 9V you can't assume it is still working correct. It might, but don't count on it. 

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I can't make sense of your LED question. You don't mention a series resistor, did you use one?A LED nearly always requires a series resistor. For starters, take 1k.