H1B Visa extension with amendment rejected

My H1B visa stamping expiry date 31-Dec-2014.

H1B Visa extension with amendment rejected on 10-Jul-2014 and returned from USA on 20-Jul-2014.(Reason for rejection not shared by employer)
So now what are my options. Am I eligible for H1B cap exempt? is there any restictions since my case is rejected? is there any time limit within which I have to apply?

Thanks