Odds are pretty good that the pin is a power pin - most pins on CPU's that I have seen are used to deliver power- in which case it will work just fine and you don't need to do anything. There's so many power pins that the incremental loss of losing one won't affect much of anything. It might have an tiny impact on overclocking, but beyond that it should work just fine.
I would look at the technical documentation on AMD's website and see if the pin is needed - or just try the part and see what happens.
If you need to repair the pin, I would highly recommend contacting AMD regarding the issue to see if it's covered under warranty or if you could pay to have it fixed. I wouldn't try fixing it yourself - there's a reasonable chance that you could destroy your motherboard by accident if you accidently short pins while trying to fix it.