I found this solution online in a "I need help with my Sylvania TV" forum. It seems that everyone had problems with their remote (lost, replace batteries, etc). They brought univeral remotes which worked fine for awhile. However, I read this answer which was interesting. I think that you might have to go this way.
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Well it took some long searching (thank you, Google) but I finally found a website that sells original, brand new Sylvania remotes at a lesser price than another site. www.electronicadventure.us
If you have model #SRT2119A, your remote model # is N0139UD. Am getting the same remote for $36 including shipping. Seems like a lot of $ but what are you going to do? They have a 30 day no hassle 100% refund policy. At remotes.com, they suggest the following can be done to "reprogram" your remote:
1) Take out the batteries.
2) Press & release each and every button one at a time until every button has been pressed at least once.
3) If you have any sliders on your remote, move each slider back & forth.
4) Put batteries back in and try remote.
I haven't tried it yet, figured I'd try it in the morning & have the remote I just ordered as backup if the reprogramming works out. Good luck, everyone!
I went to the website that the answerer indicated and saw your tv model number at that website. Here's the link