Turbo Tax says I have a federal refund of $9.9 billion dollars. Any fix for this?

I would check the W2 box 2 withholding.  Actually delete the W2 and enter it again MANUALLY.  That usually fixes it.  

Thanks so much.  I tried your suggestion and unfortunately it didn't help.  :(

Might be the withholding on a 1099?  Like a 1099R?  Besides the refund on 1040 line 35a what other lines show the big amount?  Like line 25a or 25b? 

Or it could be an entry error for the excess SS from W2s.  Do you have more than 1 W2?  Anything on 1040 line 31?

Seems like you might have typed an amount with ta comma instead of a decimal point for cents?