If you got your ticket online from bahn.de website:
You cannot opt-out from reservations for the 2nd leg of your trip from Stuttgart to Paris with TGV.
(Assuming that you will go Munich-Stuttgart-Paris)
What you did was opting out of reservations for the 1st leg from Munich to Stuttgart (which should be no big deal as most trains on that route start in Munich).
On your ticket, you should find the obligatory reserved seats for the TGV near the departure/arrival times of the Stuttgart-Paris leg.

If the print-out is in German, it will look like this:
Wagen or Wg. X=NUMBER) = car no. X
Platz XX = seat no. XX

And possibly something like "oben" or "unten" meaning upper or lower deck of the respective car (some/most TGVs on the route are double-decker trains).

How did that angry smiley got into the post?!

Maybe it works better this time:

Wagen or Wg. X (X=NUMBER) = car no. X
Platz XX = seat no. XX

And possibly something like "oben" or "unten" meaning upper or lower deck of the respective car (some/most TGVs on the route are double-decker trains).

<i>Pulkit7 on Jul 18, 14 at 6:31am
Yes the second connecting train is TGV. But they have given me the ticket. Now how to confirm whether a seat is reserved or not? You think any of that detail can be on ticket itself? </i>

As Cowboy1968 says the TGV requires a seat reservation and the ticket shows this. The are images of two SNCF TGV tickets with detailed explanations at http://tinyurl.com/eym5b. These tickets were issued in Paris so they are in French.

You may need to use the date stamp machine, even though the date is already on the ticket. I don't know what the German words for <i>BILLET à composter avant l'acces au train</i> would be.

You don't compost, err.., validate TGV tickets for journeys with TGVs in Germany or for journeys to France commencing in Germany.
If OP travels Munich-Stuttgart // change to TGV // Stuttgart-Munich there will be no stamp machine in Stuttgart. You just board the train.

I assume that OP bought his tickets online and printed them at home, so they will look like any other DB online ticket you print at home.

sorry for typo in 2nd sentence:

If OP travels Munich-Stuttgart // change to TGV // Stuttgart-<b>PARIS</b> there will be no stamp machine in Stuttgart. You just board the train.

Thank you Cowboy1968 and others. I checked the ticket and as said by you, I can find the seat numbers written in TGV information. Well, this should settle the topic.

If the TGV train is not full and seats are not reserved down the line then you can always IME change seats - like to an aisle seat or window seat, etc. You might ask the conductor if the seats are not reserved from subsequent stations though.