My 2017 tax return had rejected by IRS, and I just found out my 2016 tax return had also got rejected from E-filing. First, What can I do to fix my 2016 tax return?

[cameaf]

Since you can no longer efile your previous years' return, you will need to print, sign and mail the 2016 return in order for it to be processed by the IRS.

For the current year tax return, if you can correct the reason for the reject, there may be a chance that you can re-efile the return.  See link below that explains how to fix a rejected return:

https://ttlc.intuit.com/replies/3302275