explorer.exe is one of the most important files in windows operating system (but not the best one though). It's responsible for navigating through the file system, security attributes, permissions and so.
Go to my computer, then click your main hard drive and open windows folder, press "E" in the keybord and then you can find it.
explain your question in bit more detail .
you can create an batch file containing following code : @echo off taskkill /F /IM "Explorer.exe" exit and save tha batch file in the startup folder . This would work for windows xp and higher but an not sure for windows 2000.you can start it again manually from task manager->new Task