How to save keystroke?

string keyBuffer = string.Empty;
Int32[,] Vkey = new Int32[2,150]
 void ReadfromKeyboard()
 {
const uint MAPVK_VK_TO_VSC_EX = 0x04;
const uint KLF_ACTIVATE = 0x00000001;
   for (int i=0; i<120; i++)
      {
       if(  (Methods.GetAsyncKeyState(Vkey[1,i])== 1) ||      (Methods.GetAsyncKeyState(Vkey[1,i]) == Int16.MinValue))//Vkey is an array which store virtual key code like Vkey[1, 0] = 0x31;
             {
             uint temp =Methods.MapVirtualKeyEx((Convert.ToUInt32(Vkey[1,i])),MAPVK_VK_TO_VSC_EX,Methods.LoadKeyboardLayout(InputLanguage.CurrentInputLanguage.Culture.KeyboardLayoutId.ToString(),KLF_ACTIVATE));
            StringBuilder keyname=new StringBuilder();
            int nsize=50;
            if (Methods.GetKeyNameText(Convert.ToInt32(temp), keyname, nsize) != 0)
                      {
                          keyBuffer += keyname.ToString();
                      }

                }
        }
                if (keyBuffer != string.Empty)
                    textBox1.Text=keyBuffer;
            
  }