NeoContractTest.cs

using System;
using System.IO;
using System.Linq;
using Neo;
using Neo.VM;
using Neo.Cryptography;

namespace ConsoleApplication1
{
    class program
    {
        static void Main(string[] args)
        {
            var engine = new ExecutionEngine(null, Crypto.Default);
            engine.LoadScript(File.ReadAllBytes(@ "C: \ ... \ YourContractName.avm"));

            using (ScriptBuilder sb = new ScriptBuilder())
            {
                sb.EmitPush("doSomething");
                engine.LoadScript(sb.ToArray());
            }
            engine.Execute(); // start execution

            var result = engine.EvaluationStack.Peek().GetBigInteger(); // set the return value here
            Console.WriteLine($"Execution result {result}");
        }
    }
}