Ok, if the messages were stored on the SIM card, then you do have a chance.
You have to have a computer to do this, you cannot avoid this.
To retrieve deleted messages the first thing you need to do is stop any sending and receiving of messages's) The reason is that the deleted message messages are still on the SIM card, but if they are overwritten with a new message, then they are gone for good.
You will then need to buy this SIM USB reader so that your SMS messages can be read by a computer
You put the SIM card into this reader and put it into a computer.
You will then use the dekart program Sim Managerhttp://www.dekart.com/products/card_management/sim_manager/
It will retrieve deleted messages on the SIM that have not yet been overwritten. They will then be available on your computer
If you have any problems, or would like any additional information or assistance, please do not hesitate to let me know.
Else if you can take a second to rate my service by clicking one of the stars at the top of the screen then submit, that would be greatly appreciated.