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Hello, I'm Shahid.Sorry to hear that you're having trouble with this but I'll do my best to help.
I'm reviewing your question now, and will post back with your reply momentarily.
Vizio 550M TV does have Analog Audio Out and Digital audio (Optical) port at rear, you can connect a soundbar either in Audio Out jacks using audio cable that has red-white RCA pins or connect an optical cable into Optical port and plug it into Optical In port of soundbar (if it has one) to get TV sound through soundbar.
There are several soundbars of different brands and prices are available, you can get Vizio, Samsung or Sony brand soundbar but make sure it has analog audio input and optical input to connect it to the TV. Please click following link to view different models of Vizio brand soundbars..
Following link shows Sony soundbar range..
and below link will show Samsung soundbars..
You may please select any soundbar of your choice and price range. I hope these info will help. If you have any additional questions, feel free to ask. If you're satisfied, please rate me a 5-star at the top of your page. Thank you.