Colors change when i open.nef file?

I have a question to ask, I have a nikon D90 and have been shooting raw right from day 1, until yesterday I started facing an issue. The photos on my camera LCD look brilliant nice vibrant everything, but as i open them on my PC they look desaturated and underexposed. I shot raw + jpg yesterday. Now JPGs are exactly the same as what i see on my Camera LCD. I really need your help here. I'm so boned.
P.S. I shot all the images in sRGB color space, and i use a photoshop cs 6.

To get accurate colours on your computer, first of all you need to calibrate the monitor. Google it "How to calibrate my monitor". This is the first step, but won't address you problem per se.

My guess is that Adobe Camera RAW is set to convert the images to Adobe RGB, and if you don't know what your doing, this usually results in dull images, particularly if you view them in a browser over the internet - since the world standard for colour reproduction on the web is sRGB.

Here's how to fix your problem, Open a RAW image in Adobe Camera RAW, click on the link under the image window, where it says "Adobe RGB 1998". This will call up the settings, change the colour profile to sRGB instead. Process your image as usual, then open it in Photoshop.