2007 Mustang T5 Problem

I have a 2007 Mustang V6 with a 5-speed T5 transmission. I bought it brand new a week ago and it only has 500 miles on it.

Tonight while I was accelerating, I shifted from 2nd to 3rd and it grinded and wouldn't go into gear. I threw it in neutral and tried it again and it did the same thing. I know how to drive manual and I've never had this happen to me.... My question is; why did this happen? Did I damage my transmission? What should I do?

Did you have the clutch pedal all the way down? Will it go into 3rd at all now? Take it back to the factory if there is a problem. Sounds like you just missed a gear.

Take it back in, its under warranty

when you say you put it in neutral and then tried again, did you release the clutch when doing so?