When I filed taxes in 2014 & 2015, I did not claim tax refund on new car purchase & a motorcycle purchase. Can i file for tax refund now?

I purchased a new car in Oct 2013 and a motorcycle in Jan 2015, both in Texas.  Until now, I wasn't aware that I can claim tax refund by itemizing the deductions (on sales tax). I filed my taxes for 2014 & 15 without including the above purchases. Question is Can I file for tax refund in 2016 for the purchases I made back in 2013 & 2015, which I didn't claim yet? Appreciate your response. Thanks