log on user problem, Internet Exp disappeared, general stuff up

Recent problems after teenager (grrrrrrrrrrrrrr) been interfering on pc -
When I try to logon to my user account it freezes after I have put in password and I have to switch off power supply before it will let me get any further.
Internet Explorer 6 icon has vanished, I have to open msn to access anything.
Aforementioned teenager tells me screen went blue and everything closed down when she was using it the other day.
System restore will not let me go to any previous restore dates.

 

1. If this is XP, Control Panel > Display Settings > Desktop tab > Customize Desktop button > Check the Internet Explorer box from Desktop Icons group.

2. Go to the link below and scroll down to #278 on the left-hand side (Restore/Enable System Restore) download and run it.

http://www.kellys-korner-xp.com/xp_tweaks.htm

3. Did the "Aforementioned teenager" install or download anything?

Steve