I have a split system A/C. My unit outside has frost on the pipe and will not turn on. How can I fix this problem? Is my air conditioner ruined?

Your system has a leak. Replacing indoor or outdoor coil after leak search is performed. With luck the leak could be at valves or line copper set. Coil replacement can be expensive,age of your split system then should determan if repair or replacement is the best opption,coil leaks cannot be patched.