I'm currently in Japan and using a local data only sim.
To do so, I took my Optus sim out of my handset and put it in my wallet. I can no longer find said sim.
Optus proceedure for a lost sim starts with contacting them. However, without my sim I cannot access my Yes Optus app, cannot call the optus support number and live chat isn't working.
Wait a bit and try contact Live Chat again.
If its really urgent then call Optus on +61 2 8082 5678
It won't be free but you should be able to organise a replacement for the SIM you lost.
Thanks for reaching out and I do apologise for any inconvenience caused. Unfortunately, you'll be unable to arrange replacement SIM via Live Chat as this is a security concern. You can process this online via your My Account →https://www.optus.com.au/my-account-login or when speaking with our customer care team on +612 8082 5678.