I downloaded the Microsoft office professional trial.. It downloaded but when I tried opening it it told me that my trial has expired. I unistalled everything it downloaded then downloaded it again it told me the same thing. Does anyone know what went wrong or why I'm getting that message.

A trial version of some kind has already been used once on this computer.

If you believe that is NOT the case, send a message to Microsoft support to that effect.

I did and they weren't too much help. Is there any way I can delete everything
?

Start > Control Panel > Add/Remove Programs > Microsoft Office > Remove

I did that. It still told me the trial was expired.

You mean you reinstalled it again? That won't work.