(Sorry for my English) I upgraded the memory ram from 1gb to 2gb, but when I turn on the computer it makes 3 beep sounds, the fan doesn't stop turning and the boot up screen doesn't appear. The problem is persisting even after have returned with the original memory. I have tried every method like trying every slot, only one module, and also with the new modules but with no success. According to this site 3 beeps means ram failure: http://www.computerhope.com/beep.htm
You've tried every possible combination of RAM slots and memory? Something must work, if not then I'd recommend a BIOS reset.
unplug the computer take the battery out wait 10 minutes put it back and try again but.......... did you earth yourself before moving the ram, it is very possible you have inadvertently blown your motherboard
what computer and what ram modules have you got, did you replace old for new? If not what sticks do you have (Description)