Have you tried all the codes listed in the remote's user manual for RCA models?
Which remote model do you have, S10 which requires 4-digit codes or s20/s30 which require 5-digit codes?
If none of the codes in the remote's user manual work google search for x digit codes for RCA model, where x is 4 or 5 depending on your remote model and model is your RCA tv model. These kind of searches find tables which may provide multiple codes to try (not necessarily for your specific tv model) some of which most likely are some of the same as in the remote's manual. No guarantees you will find one that works however.
Note, if you lost the remote manual you can find it's pdf to download from here.
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