Internet Explorer not working

I have Windows ME on my Intel Celeron 2Ghz desktop PC.
Recently, a friend of mine (I thought he was really tech
savvy) did some editing in my system registry and since
then my internet explorer has stopped working. I have a
broadband internet connection (128kbps) and have been
reconfirmed by the service provider that the service is
running.

After connecting to the internet, whenever I open the
Internet explorer and type any website name, it instantly
gives "this page can not be be displayed" error.

Please help me out of this deadlock !! Many thanks in
advance.