TN holder lost I-94TN when I am in 3rd country.

Hi,

I am in 3rd country for vacation (not US or Canada), I lost my I-94TN somewhere, but there is still a TN stamp on the canadian passport. I want to know if I have trouble when I re-enter US with international flight. Anyone has similar experience?

As long as the stamp has your I-94 number, the CBP officer should be able to trace it.

Your I-94 should have been given back when you left in any event, so you always need to keep a separte record of your TN number, for re-entry.