I am in Switzerland and have a UK Dell laptop. It has been working fine with a EU plug adaptor on the UK plug. Now when I try to turn on the power on my laptop, it will not fire up. I get a red light come one showing the battery indicator. What does this red light mean? If I hold down the power on button for 3 - 5 seconds, the red light still comes on together with a blue light on the power button but still nothing comes up on the screen. What does the lights mean? I do not know what is going on here. Please help! Thanks very much.

It is possible that it is not getting power from the plug, and the battery is run down.
Tell us what model of Dell, the configuration, and perhaps the perhaps the service tag number, as well as the age of the hard drive and screen.
But from what you describe, it is either not attempting to boot, or it is booting but there is nothing on the screen.

With the unit off, and the power adapter plugged in, see if you can feel any looseness at the power socket. Sometimes that socket comes loose and will not accept power.
Hold down the power battery for 15 to 20 seconds without letting up. That will clear the unit thoroughly.
When you attempt to reboot, listen in a quiet environment. We would like to know if you detect any noise typical of the hard drive booting up.
Then let us know if there is still a dark screen.