Timers in TM4C123G not working
Also here is some example code for TIVA Timer setup. You might be able look at this and get some idea

#define TIMER0_CFG_R            (*((volatile unsigned long *)0x40030000))
#define TIMER0_TAMR_R           (*((volatile unsigned long *)0x40030004))
#define TIMER0_CTL_R            (*((volatile unsigned long *)0x4003000C))
#define TIMER0_IMR_R            (*((volatile unsigned long *)0x40030018))
#define TIMER0_MIS_R            (*((volatile unsigned long *)0x40030020))
#define TIMER0_ICR_R            (*((volatile unsigned long *)0x40030024))
#define TIMER0_TAILR_R          (*((volatile unsigned long *)0x40030028))
#define TIMER0_TAPR_R           (*((volatile unsigned long *)0x40030038))
#define TIMER0_TAR_R            (*((volatile unsigned long *)0x40030048))
#define TIMER_CFG_16_BIT        0x00000004  // 16-bit timer configuration,
                                            // function is controlled by bits
                                            // 1:0 of GPTMTAMR and GPTMTBMR
#define TIMER_TAMR_TAMR_PERIOD  0x00000002  // Periodic Timer mode
#define TIMER_CTL_TAEN          0x00000001  // GPTM TimerA Enable
#define TIMER_IMR_TATOIM        0x00000001  // GPTM TimerA Time-Out Interrupt
                                            // Mask
#define TIMER_ICR_TATOCINT      0x00000001  // GPTM TimerA Time-Out Raw
                                            // Interrupt
#define TIMER_TAILR_TAILRL_M    0x0000FFFF  // GPTM TimerA Interval Load
                                            // Register Low
#define SYSCTL_RCGC1_R          (*((volatile unsigned long *)0x400FE104))
#define SYSCTL_RCGC1_TIMER0     0x00010000  // timer 0 Clock Gating Control

void DisableInterrupts(void); // Disable interrupts
void EnableInterrupts(void);  // Enable interrupts
long StartCritical (void);    // previous I bit, disable interrupts
void EndCritical(long sr);    // restore I bit to previous value
void WaitForInterrupt(void);  // low power mode
void (*PeriodicTask)(void);  // user function
// ***************** Timer0A_Init ****************
// Activate Timer0A interrupts to run user task periodically
// Inputs:  task is a pointer to a user function
//          period in usec
// Outputs: none
void Timer0A_Init(void(*task)(void), unsigned short period){ 
  SYSCTL_RCGC1_R |= SYSCTL_RCGC1_TIMER0; // 0) activate timer0
  PeriodicTask = task;             // user function 
  TIMER0_CTL_R &amp;= ~0x00000001;     // 1) disable timer0A during setup
  TIMER0_CFG_R = 0x00000004;       // 2) configure for 16-bit timer mode
  TIMER0_TAMR_R = 0x00000002;      // 3) configure for periodic mode
  TIMER0_TAILR_R = period;         // 4) reload value
  TIMER0_TAPR_R = 49;              // 5) 1us timer0A
  TIMER0_ICR_R = 0x00000001;       // 6) clear timer0A timeout flag
  TIMER0_IMR_R |= 0x00000001;      // 7) arm timeout interrupt
  NVIC_PRI4_R = (NVIC_PRI4_R&amp;0x00FFFFFF)|0x40000000; // 8) priority 2
  NVIC_EN0_R |= NVIC_EN0_INT19;    // 9) enable interrupt 19 in NVIC
  TIMER0_CTL_R |= 0x00000001;      // 10) enable timer0A
  EnableInterrupts();
}
void Timer0A_Handler(void){
  TIMER0_ICR_R = TIMER_ICR_TATOCINT;// acknowledge timer0A timeout
  (*PeriodicTask)();                // execute user task
}


On the TIVA, TM4C123GH6PM micro controller Port F is a special port. PF0 on TIVA need to be unlock. 


Click on image for a larger version of the image. 

Below is example code. 

void PortF_Init(void){ volatile unsigned long delay;
  SYSCTL_RCGC2_R |= 0x00000020;     // 1) activate clock for Port F
  delay = SYSCTL_RCGC2_R;           // allow time for clock to start
  GPIO_PORTF_LOCK_R = 0x4C4F434B;   // 2) unlock GPIO Port F
  GPIO_PORTF_CR_R = 0x1F;           // allow changes to PF4-0
  // only PF0 needs to be unlocked, other bits can't be locked
  GPIO_PORTF_AMSEL_R = 0x00;        // 3) disable analog on PF
  GPIO_PORTF_PCTL_R = 0x00000000;   // 4) PCTL GPIO on PF4-0
  GPIO_PORTF_DIR_R = 0x0E;          // 5) PF4,PF0 in, PF3-1 out
  GPIO_PORTF_AFSEL_R = 0x00;        // 6) disable alt funct on PF7-0
  GPIO_PORTF_PUR_R = 0x11;          // enable pull-up on PF0 and PF4
  GPIO_PORTF_DEN_R = 0x1F;          // 7) enable digital I/O on PF4-0
}


Please take note of 


  GPIO_PORTF_LOCK_R = 0x4C4F434B;   // 2) unlock GPIO Port F


Also I suggest you sign up for Embedded Systems - Shape The World. They use TIVA and it is great semi self-paced course. 

References


Parallel I/O ports
Embedded Systems - Shape The World
Timer Examples
How to unlock Port F pins 0 and 4 of Tiva C series TM4C123G to register SW2 and SW1 switch press?