I was having trouble with my internet and was told it was the network card so I installed a new card . After I installed the card I hooked up the monitor, printer , etc. to the computer and now my monitor will not work. I thought maybe it was the monitor but I tried a second monitor and it will not work either. What could I have done?

Have you tried to remove the card you added to see if the monitor would work without that card present?

If you take out card and monitor works, it has to be something with the card itself.

Did you install a "new" known working card? Has this card been installed in another computer and it worked?

As far as the moitor card goes, take out the card and see if monitor works or not

Does the computer boot and did you unplug the power cord before swapping the network card? If not, the motherboard may be blown.

It is a new network card a Linksys NC-100 and the machine is an Emachine with windows XP. I did unplug the box and everything was unhooked from it when I inserted the network card.

I did remove the card and now neither monitor works when attached and they both worked before.

You can hear the computer boot up but the monitor will not light up, one monitor just has the green light and it blinks the other monitor has a blue screen with a plug with a line through it meaning it is not plugged in but it is. I have unplugged and plugged severa times and still nothing.
Thanks for your help.

The other thing to look at now is the video card, is it an onboard video card or an actuall video card. If it is onboard video, you could try an actual video card.

If you have a video card in there now, see if you can swap it out with a known working video card and see if that is the problem

You could have loosened or shorted the video card. Make sure its seated properly, if it is you might have to replace it.

This is my daughters computer, she says the light is on for the network card. She checked to see if she could unplug the video card but it is one that is not able to unplug but it looks like it is not loose. Everything worked perfect except for the internet before she replaced the network card and she did not touch anything other than to plug the network card in. She did say the old place where the network plugged in she was unable to unplug it or remove it because it is just a metal casing with a box in it attached to the frame. Not sure if this makes sense, I am just trying to find things for her to try to help her get up and going again. Her computer is about 5 years old.

The video card and any card should be attached to the case with a small screw, usually a philips head.
Examine where the card is pluuged into and follow the card along the top and she should be able to see where the card itself is attached to the case, unscrew that and then with even pressure pull the card out or in, depending on what you are doing.

Try and move the card to othere slots to see if that would help, it is possible something got shorted, basically try other slots and just get the video working first, if and when video is worked out, focus on net card

Did the network card some with software? The new card may have not been seen by the PC as it might need drivers for it to work

Thank you, the network card has software with it but without the monitor she is unable to load the drivers, or will it load without the monitor? I will pass your info on to her. Thank you, will let you know what happens.

She took the graphic card out and put it back in and it made no difference. And she is not able to load the drivers for the network card without the monitor. Thanks for your help.

Has she tried to put the video card in another slot, if so and same results, it may be the video card itself