Hi Sunil,
You will need an Analog Sterio Cable to connect from your Home Theater to the Samsung TV. Once you have done that you will need to change sound settings in your TV, for that follow below steps:
1. Turn the TV on, and then press MENU on the TV remote. [The Main Menu appears]
2. Press the [Down Arrow] to highlight the Sound menu, and then press ENTER.
3. Press the [Down Arrow] to highlight Speaker Settings, and then press ENTER.
4. Press the [Down Arrow] to highlight Speaker select, and then press ENTER.
5. Press the [Down Arrow] to highlight External, and then press ENTER.
6. Press EXIT to return to the TV picture. The sound is now coming out of the speakers.
I had that same problem with my Samsung TV and I found this info at the below link and its working fine now:
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http/www.samsung.com/us/support/supportOwnersHowToGuidePopup.do?howto_guide_seq=5960&prd_ia_cd=N0000044&map_seq=36928®Dt=20111116122142&page_gb=D&model_name=SPL4225&type_ia_cd=N0000042&subtype_ia_cd=N0000044&row_index=4
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