I complete my bachelor degree in August 2015. At that time I have TPS, so I did not apply for OPT. I have not taken any classes. Now when reapply for F1 status when TPS end can I get my OPT?
really appreciate any advice!

If you have maintained you F1 status, you are still in valid F1 status (you did not mention about using EAD through TPS, my guess is you did not take minimum credit course while on TPS and started working full time), you should get OPT (since you already have EAD, you are applying for OPT through F1). However, check you SEVIS status to confirm.

I would rather recommend you to consult your international Adviser and if needed, surrender your TPS with EAD and remain in F1 and apply for OPT.

I don't think so. You might get your F1 status back but your OPT is gone. Double check with some GOOD lawyer but they probably will tell you the same.

Thanks Nirman and Nepal USA!