You have either knocked a component or connector loose, or have moved a connector from where it should be. Possibly you have done both!
You need to consult the motherboard manual for your PC (or download it from the motherboard manufacturers website if you haven't got it) and check that all wires and connectors are correctly attached to the appropriate pins.
You then need to check that all expansion cards and cable connectors are firmly and securely pressed 'home' in their sockets.
Catweazle
Grandad
4,335 posts since Mar 2004
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The HDD LED connection is nothing more that the connection which goes from your motherboard to the hard drive activity indicator light (LED; Light Emitting Diode) on the front of your chassis. Having it disconnected has nothing to do with your problem; although reconnecting it to the wrong points on the motherboard could.
The "no signal" message from your monitor means that it isn't getting a valid signal from your video card. With everything else you've described, it sounds, as Catweazle said, that you've either knocked a connection or component loose or have mis-plugged something when you reconnected your wiring.
As mentioned, you'll have to check the documentation for your particular motherboard to determine the correct connections; those vary between different makes/models of motherboards.
DMR
Wombat At Large
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Catweazle
Grandad
4,335 posts since Mar 2004
Reputation Points: 229
Solved Threads: 149