Email with DHL Tracking Number - virus?

I just got this email:

Subject: DHL Tracking Number B670BS9K

Body: Hello!

Unfortunately we were not able to deliver the package you have sent on the 3rd of June in time
because the addressee's address is not correct.
Please print out the invoice copy attached and collect the package at our office.

Your DHL Delivery Services.

There was a .txt file attached. Stupidly, I opened it. There was no text inside. I did a Google search and it said that it contains Malware. Does anyone know if this affects Mac OS users? Should I go back in time (using my Time Machine).... or am I okay?

 

Thanks. Strangely though, I just went into Time Machine for the heck of it and... as soon as I'm in there, I can't do anything. I can't go back or anything. It's just froze. I have to do command-Esc to get out. I've restarted and same thing. Why might that be? Or what could I do to fix that?

Edit: Actually... just curious... how can I completely restore my system from Time Machine? Unless I choose a specific file... the restore is grayed out...?