Xperia Pro/Neo/V/L :: Its Not Switching On

I have a Xperia Neo L. I have used it for about half a year and there never has been any problems. However, since yesterday, after I switched off my phone. I was not able to turn it back on again. When I held down the power button, there was a vibration, which was normal, but there is nothing on the screen. The screen is just totally black. When I tries to charge my phone to see what happens, there is still the orange light on top, but my phone still does not switch on. I tried calling myself, but it claims that my phone is switched off. When I link my phoner to the computer, my phone will still have the orange light on top, signifying that it is being charged, but when I check my computer, I cannot find my phone(the file-removable disc(:/F))