FreeRTOS software timer not working

Hey guys I am Anup and i am a student. I am new to freeRTOS concepts. I am using STM32F407VGTx board and i want to implement Software Timers to blink the LEDs using Keil software. I am creating the software timer and then I am starting the timer. As per the concepts the software timer should call the callback function as soon as the timer has expired but this is not happening with my code. I have pasted my main.c and the software timer configurations in freeRTOSconfig.h below. Do see that and tell me what I am doing wrong soon. Thanks in advance.
#include "stm32f4xx_hal.h"
#include "cmsis_os.h"
osThreadId defaultTaskHandle;
osTimerId mytimerHandle;
void SystemClock_Config(void);
void Error_Handler(void);
static void MX_GPIO_Init(void);
void StartDefaultTask(void const * argument);
void myfn(TimerHandle_t mytimer);
TimerHandle_t mytimer = NULL;
int main(void)
{
    printf("dsfsdfsdfsd");
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  osThreadDef(defaultTask, StartDefaultTask, osPriorityNormal, 0, 128);
  defaultTaskHandle = osThreadCreate(osThread(defaultTask), NULL);
  osKernelStart();
  while (1)
  {
  }
}
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct;
  RCC_ClkInitTypeDef RCC_ClkInitStruct;
  __HAL_RCC_PWR_CLK_ENABLE();
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = 16;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
  HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
  HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);
  HAL_NVIC_SetPriority(SysTick_IRQn, 15, 0);
}
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct;
  __HAL_RCC_GPIOC_CLK_ENABLE();
  __HAL_RCC_GPIOH_CLK_ENABLE();
  __HAL_RCC_GPIOD_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
  HAL_GPIO_WritePin(GPIOD, GPIO_PIN_12|GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15, GPIO_PIN_RESET);
  GPIO_InitStruct.Pin = GPIO_PIN_12|GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
}




void StartDefaultTask(void const * argument)
{
**     vTaskStartScheduler();
     mytimer = xTimerCreate( "Timer" , pdMS_TO_TICKS( 500 ) ,pdTRUE, "123" , myfn);
     xTimerStart( mytimer, 0);**
}

**/* myfn Callaback function */
void myfn(TimerHandle_t mytimer)
{
    HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_12|GPIO_PIN_14|GPIO_PIN_15);
}**




void Error_Handler(void)
{
  while(1) 
  {
  }
}

void assert_failed(uint8_t* file, uint32_t line)
{
}





/* Software timer definitions. */
**#define configUSE_TIMERS  **                               1
**#define configTIMER_TASK_PRIORITY**                ( configMAX_PRIORITIES - 1 )
**#define configTIMER_QUEUE_LENGTH  **              10
**#define configTIMER_TASK_STACK_DEPTH**         256

FreeRTOS software timer not working

This is very hard to answer as you are not using the native FreeRTOS API. I don’t know what osThreadDef() is doing, but a quick Google search would seem to indicate it is defined as:
#define osThreadDef (       name,
    priority,
    instances,
    stacksz
)       
You are calling:
osThreadDef(defaultTask, StartDefaultTask, osPriorityNormal, 0, 128);
so it seems you are setting the priority to StartDefaultTask. These are not FreeRTOS APIs though, so falls outside of FreeRTOS support. I cannot see defaultTask being defined anywhere. Is it just a name? Is StartDefaultTask support to be the actual task? If so then it needs to be implemented as described here: http://www.freertos.org/implementing-a-FreeRTOS-task.html