If you only have a single instance of Splunk on your machine, chances are you configured the input but perhaps its not in the normal system configuration location. The configuration should still see it, you can check
*Settings -> Forwarding and Receiving -> Configure Receiving *
Alternatively, from the CLI you can do
$splunk_home/bin/splunk btool inputs list splunktcp --debug
Run that from the bin directory where Splunk is installed. That will show you all splunkTCP inputs configured and the configuration file it exists in. You can remediate from there.
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