Win7: Editing File Class W/out Admin Pw?

Hi! I have a Windows 7 64-bit laptop at a day program. I've been able to associate a file class to an application using Open With.... However, I have not been able to have a program associate a file class to itself without an administrator password. I also can't run RegEdt32. Is there a way to add a description, an application and an icon to a file class without the password?

 

Do you own the computer?

 

I do own the computer. My day program gave it to me for my own personal use, but it was pre-owned, and the staff who gave it to me didn't have the password, and probably the staff couldn't get into contact with the previous owner.

 

Do you have a Windows 7 installation disc?

 

No. If I use one, will it delete all my information on the computer?