That won't work if the administrator profile is password protected as you'll be requested to enter a valid administrator password.
Under Windows XP, it's not a problem as by default you always are working with administrator privileges.
Under Windows Vista and 7, the default is a restricted level and you need to escalate to administrative privileges to change system whide things, like installing drivers.
You may be able to bring it to a computer shop and have them do a password reset. It won't be free and you'll need to give some proof that it's realy your computer.
For your inhability to access several sites, take a look at the file:
C:\Windows\system32\drivers\etc\hosts (extention-less text file)
If a blocked site appears in a line starting with 127.0.0.1, suppress that line. Save the file, the effect is immediate, you don't need to restart the computer.
Do you connect via a router?
Check it's configuration, it may be set to only allow access to a few sites (using a small white list), or to prevent access to several sites (using a to broad black list).
Check the settings of any firewall present.
Electro
April 2012