You are getting closer to code that might actually compile. Like everyone else, I don't fully understand what you are trying to do so electronically I am not sure it will work.
You are still not setting you pinmodes for the switches correctly.
You declare SwitchPinA, B and C. In your setup, you set pinmode for switchpin. This is not correct.
You're trying to use software serial but you have not set it up right. Are you using software serial or are you using the actual serial pins on the Arduino. This makes a big difference in how you code it. If you are actually using software serial then you have to declare it and start it:
SoftwareSerial mySerial(-1,?); //The ? should be whatever pin you have attached to your LCD.
And in the setup:
mySerial.begin(9600);
Further down you are calling a function that doesn't exist when you call mySerial.write_string();
These forums are great for helping you out in a jam or pointing you to resources that will help you get started but you are being too ambitious for your skill level which is clearly none.
Open up all of the examples in the IDE and try to figure out what they do. If you can't turn an LED on and off using a switch which you can't based on your code, the people on this forum are not going to do it for you. You have to be willing to learn what to do and let us help you get unstuck instead of just posting crap and hoping we will re-write it for you.