I want to make a "Reset cold" and right after that a "Start" in the plc code.
What are the variables for these symbols?
You should be able to use the FB PLC_Reset and FB PLC_Start in the TC2 utilities library.
You may however experience an issue restarting the code if the PLC is not running after the reset as it then can't run the PLC_Start command on itself. You may have to run the start command from another system and/or using Beckhoffs ADS interface.