My internet won't open...?

I cannot open my internet on my Toshiba laptop. It has Windows XP. I CAN open it, however, under another username on my computer. But my login is the system administrator so I can't do anything under the other login and also all my documents, music, pictures, are all under my login. I've looked on ask a geek type websites but all the similar questions require downloading something form the internet to fix the problem but how am I supposed to do that if I can't open the internet......??? I've tried right clicking on it to open and also through the startup menu but to no avail. There are no error messages that pop up either. Also, under my username the computer runs extremely slow. I've tried doing a virus and spy scan and they both came up clean. Can anyone help???