We have this double station blowing extrusion molding machine. There's a problem in plc where the battery has turned off so the program is lost.

 

In every PLC, there should be a flash card programmed to upload the latest program when battery is exhausted and power is interrupted. So that when power is restored, you still have the program coming from the flash card. This is the main purpose of having a PLC or DCS. If there is no flash card, then the only way is to get the program from where you acquired your PLC (hopefully they still have it). It's not free anyway..