If you received a bona fide notice that states your trial modification was approved, then you have a valid defense against the foreclosure.
Your lender is 'estopped' from foreclosing on you, because it agreed to modify the terms of your loan. In addition, they are in breach of your new loan modification contract.
You also mention a 'trial modification.' Was this a Home Affordable Modification Program (HAMP) loan modification?
The lender need not be the original lender, but it must have an 'endorsed' note evidencing its 'holder' status. Sometimes the note will be recorded along with the mortgage in land records. And sometimes a copy of the note will be included in the foreclosure complaint. But sometimes the lender lacks a copy of the note, or the lender has the note but it is not properly endorsed. This can also provide a defense.
Don't hesitate to find a Louisiana lawyer in your area.