If you have not earned any income in 2016 you do not need to file a return. However, any income, no matter the source (including income from abroad) would be reportable in the US, if you meet the substantial presence tet.
For 2015 you were a nonresident alien (the first two years on J1 you area nonresident alien) and would have had to file form 1040NR or 1040NR-EZ plus form 8843. Since these are not supported by Turbotax, you most likely filed the wrong return for 2015 and will need to amend.
