What do you mean "my 2016 taxes were rejected"? Are you saying that the e-file of the 2016 return was rejected a year ago? Or did you try to e-file them now (only 2017 is open for e-file at present).
Or do you mean something else by "rejected", like you got a letter from the IRS challenging something on the 2016 return?
Continue to file your 2017 return.
As for your 2016 return, it is normally an independent process from 2017 returns. If your 2016 return was rejected for e-filing a year ago, then you haven't filed it yet. You need to print and mail the 2016 return to the IRS.