How to change TWI pins to GPIO and vice versa?

Question

Hi, 
 I am working with MLX90615 sensor and is working with nrf_drv_twi functions and I could collect data as well. Now I need to put the sensor to sleep mode. Entering to sleep mode is given below. 
 
 I would like to collect the data from the sensor, put the sensor to sleep, send the collected value through BLE wait for 5-10 seconds, wake up the sensor and repeat the steps. 
 The main function I have written is as below. 
 while(1){
reg=0x27;
 err_code=nrf_drv_twi_tx(&twi_instance, 0x5B, &reg, sizeof(reg), true); // sending register
 m_xfer_done=false;
 if(device_found == true) // happens at TWI handler
 {
 device_found=false;
 
 err_code = ble_nus_string_send(&m_nus, Obj_temp, sizeof(Obj_temp));
 // MLX_SLEEP();
 nrf_delay_ms(200);
 // nrf_delay_ms(2000);
 // nrf_delay_ms(2000);
 // MLX_WAKEUP();
 // nrf_delay_ms(200);
 
 
 }
 reg=0xc6; // sleep command
 err_code=nrf_drv_twi_tx(&twi_instance, 0x5B, &reg, sizeof(reg), true); // sending register
 nrf_delay_ms(2000);
 nrf_delay_ms(2000);
 
 
 nrf_drv_twi_disable(&twi_instance); // disable 
 nrf_gpio_cfg_output(DEVICE_SCL_PIN); // keep SCL pin high during sleep
 nrf_gpio_pin_set(DEVICE_SCL_PIN);
 
 
 // wake up the sensor
 nrf_gpio_pin_clear(DEVICE_SCL_PIN); //make the pin LOW
 nrf_delay_ms(40); // wait for some time
 nrf_gpio_cfg_input(DEVICE_SCL_PIN,NRF_GPIO_PIN_PULLUP); //enable pull up
 nrf_gpio_input_disconnect(DEVICE_SCL_PIN); // disconnect gpio
 twi_init(); // initialise twi
 nrf_delay_ms(40);
 
 }
 
 Twi initialisation is given below. 
 void twi_init (void)
{
 ret_code_t err_code;
 
 const nrf_drv_twi_config_t twi_config = {
 .scl = DEVICE_SCL_PIN,
 .sda = DEVICE_SDA_PIN,
 .frequency = NRF_TWI_FREQ_100K,
 .interrupt_priority = APP_IRQ_PRIORITY_HIGH
 };
 
 err_code = nrf_drv_twi_init(&twi_instance, &twi_config, twi_handler, NULL);
 APP_ERROR_CHECK(err_code);
 
 nrf_drv_twi_enable(&twi_instance);
} 
 
 Is there anything that I am missing because this code is not working. It is going to sleep but not waking up.