Firstly, please make sure you have enough credit to send SMS.
If you still can’t send/receive SMS please check the Message Centre Number (MCN) in your SMS settings – it should be +61469000111 for Lycamobile Australia.
If you see a different number, enter +61469000111 and turn your handset off and on and re-try sending any unsent SMS.
If the problem remains please contact Customer Services.