I had my valve cover gasket replaced and new spark plug wires put on my car last week. its a 95 civic. it was running fine before taking it in but that very night it overheated and then did again today. on top of that it's idling rough at times. when i checked the radiator, both times it was completely out of coolant and i noticed this last time that the fan motor is not coming on. Could something have not been hooked back up right when i had this work done?

 

There is nothing intrusive to the cooling system when replacing valve cover gaskets or spark plug wires. If your car is overheating I would do a couple things immediately.
1) Is the car smoking? (white smoke)
2) Diag your overheating problem by checking to make sure your fan and fan relay are working properly.
3) Check to make sure your fan switch is not at fault
4) Pressure test your cooling system
5) Perform a leakdown test to check for possible head gasket issues

From my experience I would lean towards your 1) fan switch or 2) your fan relay as culprits to your problem. If oil has leaked onto the fan switch then that could be causing it not to function correctly. The third and least likely cause is the fan motor being bad. It is very important that you have your cooling system checked immediately to verify whether or not you are losing coolant through an external leak. After that the leakdown test will confirm the condition of your headgasket. It is possible that when you overheated the headgasket blew and the coolant is burning off in the cylinders causing the rough idle.