This is the most common method for legitimate recovery services. The S7-1200 uses an SD card for firmware updates and program transfer. Sophisticated engineers have discovered ways to manipulate the file structure on this card to reset the PLC to factory defaults.
If you're using Siemens software tools like TIA Portal (Totally Integrated Automation Portal), STEP 7, or SIMATIC Manager, you can try the following: s71200 password unlock top