Hi
here is some apps / writings about this issue. Maybe you could utilise those if you still have events and/or internal events on your instance.
Slackbot 17:08
There are a lot of options for finding hosts or sources that stop submitting events:
Meta Woot! https://splunkbase.splunk.com/app/2949/
TrackMe https://splunkbase.splunk.com/app/4621/
Broken Hosts App for Splunk https://splunkbase.splunk.com/app/3247/
Alerts for Splunk Admins ("ForwarderLevel" alerts) https://splunkbase.splunk.com/app/3796/
Monitoring Console https://docs.splunk.com/Documentation/Splunk/latest/DMC/Configureforwardermonitoring
Deployment Server https://docs.splunk.com/Documentation/DepMon/latest/DeployDepMon/Troubleshootyourdeployment#Forwarde...Some helpful posts:
https://lantern.splunk.com/hc/en-us/articles/360048503294-Hosts-logging-data-in-a-certain-timeframe
https://www.duanewaddle.com/proving-a-negative/
r. Ismo