Switching From RS232 to I2C and back

My code doesn't seem to be working. Using MSP430F169 trying to get a 1 one I Press 'd'  after switching from I2C Back to RS232

void main(void)
{
   WDTCTL = WDTPW + WDTHOLD;  // Stop watchdog timer
   InitUSART0();              // Initialize Serial UART Port 0
  
   
   _EINT();                   // Enable interrupts
}

// UART0 RX ISR
#pragma vector=USART0RX_VECTOR
__interrupt void usart0_rx (void)
{
   
 
  int flg_a = 0;
 
   if (RXBUF0 == 'd')                        // 'u' received?
  {
        InitI2C();
       flg_a = 1;
  
        DeInitI2c();
    InitUSART0();
     UART_transmit ('1');
 

  }
 if (flg_a == 0)
  {
        UART_transmit (RXBUF0);
  }
}

void DeInitI2c(void)
{
        U0CTL &= ~(I2C + SYNC);         ///// 1) Clear I2C, SYNC, and I2CEN (CLR.B &U0CTL)
        U0CTL &= ~I2CEN;
        UCTL0 |= SWRST;                ///////2) Set SWRST (MOV.B #SWRST,&U0CTL)
     
 
}
void InitI2C(void)
{
    P3SEL |= 0x0A;                            // P3.1,P3.3
    UCTL0  |= SWRST;
      U0CTL |= (I2C + SYNC);                    // Switch USART0 to I2C mode
      U0CTL &= ~I2CEN;                        // Recommended init procedure - Disable I2C
        U0CTL |= I2CEN;                         // Enable I2C, 7 bit addr,
}
void InitUSART0(void)
{
    P3SEL |= 0x30;                             // P3.4,3.5 = USART0 TXD/RXD
     UCTL0  |= SWRST;
      ME1 |= UTXE0 + URXE0;                     // Enabled USART0 TXD/RXD
      UCTL0 |= CHAR;                            // 8-bit character, SWRST=1
      UTCTL0 |= SSEL0;                          // UCLK = ACLK
      UBR00 = 0x03;                             // 9600 from 1Mhz
      UBR10 = 0x00;                             //
      UMCTL0 = 0x4A;                            // Modulation
      UCTL0 &= ~SWRST;                          // Initialize USART state machine
      IE1 |= URXIE0 + UTXIE0;                   // Enable USART0 RX/TX interrupt
      IFG1 &= ~UTXIFG0;
     
     
    
}

void UART_transmit (unsigned char Transmit_Data)              //UART1 Transmit Subroutine
{
     TXBUF0 = Transmit_Data;                   //send data
}