did you unplug power cord from the computer before adding the RAM? modern computers remain powered even though they are turned off. replacing components with the power on can damage large parts of your system. you have to disconnect the power cord first.
assuming that you had disconnected the power, if you have removed the added RAM and it still doesn't come up, you've fried something anyway, probable CPU or the motherboard. if you haven't removed the new RAM, do so, with the power disconnected first.
I got home today and got some ram (apparently the wrong kind) I popped it in and when i did it went to start up and didnt even get to loading screen and then just turned off. Now when i hit the power button the fans and everything turn on But after 2 seconds it just turns off.. and it wont turn on again unless i unplug it and replug it in. But it just keeps turning off and never reaches the loading screen. I tried resetting cmos and taking the battery out and Disconnecting power to motherboard. Also the power supply is only 6 months old. I have a XP1800 Processor, Abit Kr7a Raid motherboard, and 1 stick of 512 pc2100 ram. Any suggestions to what the problem could be?