how to call multiple methods using loop, please help

If I assume your goal here is to come up with a way to call various methods using a selector argument:

using System;
using System.Collections.Generic;

namespace YourNameSpace
{
    public static class TestClass
    {
        static TestClass()
        {
            IntToAction = new Dictionary<char, Action>
            {
                {'a', Journal1},
                {'b', Journal2},
                {'c', Journal3}
            };
        }

        public static Dictionary<char, Action> IntToAction; 

        // 'args set to null here so they can be ignored
        public static void Test(string[] args = null)
        {
            for (char theChar = 'a'; a < 'd'; a++)
            {
                // invoke the method selected by the char Key
                IntToAction[theChar]();
            }
        }

        public static void Journal1()
        {
            Console.WriteLine("a");
        }

        public static void Journal2()
        {
            Console.WriteLine("b");
        }

        public static void Journal3()
        {
            Console.WriteLine("c");
        }
    }
}

This example of "method dispatch" uses a Dictionary where the Key is Type 'char, and the Value is Type Action (with no parameters). Dictionaries in .NET provide very efficient look-up.

'Action is a type of Delegate that allows a more terse declarative syntax. See the solution here by C. Pallini for an example of using Delegates.

What exactly is wrong with the obvious version?

public static void Main(string[] args)
{
    Journal1();
    Journal2();
    Journal3();
}
 
public static void Journal1()
{
    console.write("a");
}
public static void Journal2()
{
    console.write("b");
}
public static void Journal3()
{
    console.write("c");
}

Please edit your question to make more clear what you're trying to prevent.

You could invoke multiple methods in a loop using reflection.
However, your entire design is wrong here.

These methods do the same thing i.e. print a character.
Thus, you should have a single method and then call that method with a parameter.

Something like

public static void Main(string[] args)
       {
           for (int i = 1; i<=5; i++)
           {
                   Journal(i);
           }
       }
 
public static void Journal(int count)
       {
           if (count == 1)
           {    
             console.write("a");
           } else if (count == 2) {
             console.write("b");
           } // and so on. Better to use a switch case rather than if
       }