Thank you so much, I'm able to drive the screen and light up any pixel I want on screen. I think I was misusing i2cwrite command on my code. Now its ok.
Here is my trial code for blinking any line on the screen.
Code:
   
'==========================MCU SETUP============================================  
Include "modedefs.bas"
DEFINE OSC 16
DEFINE I2C_SLOW 1 'Used to work with 100KHz devicez when using over 4MHz (my screen working without this too)
DEFINE I2C_HOLD 1 'Holding Lines low when not sending data (not necessary)

OPTION_REG=0
ADCON0=0
ADCON1=7
TRISA=%00111111
TRISB=%00000001
TRISC=0
PORTC=$FF

'==============================Variables=======================================

I2CDevice var byte
SCL var PortC.3         ' I2C Clock  PortC.3
SDA var PortC.4         ' I2C Data   PortC.4
DC VAR byte' "DATA OR COMMAND", $40=DATA; $80=COMMAND
LCD_DATA VAR BYTE
COM VAR BYTE' COMMAND


I VAR BYTE
J VAR BYTE
X VAR BYTE' LCD Column POSITION (0 TO 127)
Y VAR BYTE'LCD Line POSITION FOR PAGE MODE(0 TO 7)
CLEAR
'=============================================================================
I2CDevice = $78      ' Display = $78,
PAUSE 20
'=========================lcd initialization====================================
INIT:
I2CWrite SDA,SCL,I2CDevice,[DC,$AE]'Display Off
pause 10
I2CWrite SDA,SCL,I2CDevice,[DC,$20,$10]' Page adressing mode
I2CWrite SDA,SCL,I2CDevice,[DC,$D3,$00]' Set offset to 0
I2CWrite SDA,SCL,I2CDevice,[DC,$40]' Set display start line 0
I2CWrite SDA,SCL,I2CDevice,[DC,$81,$FF]' Set contrast to full
I2CWrite SDA,SCL,I2CDevice,[DC,$A4]' display on continue 
I2CWrite SDA,SCL,I2CDevice,[DC,$A6]' $A6=NORMAL MODE;$A7=INVERSE MODE
I2CWrite SDA,SCL,I2CDevice,[DC,$A1]' set column 127 as start
i2cwrite sda,scl,I2CDevice,[DC,$C8]'Flip display vertically ****
'above 2 lines for arranging screen direction, deleting them will
'turn the display direction 180 degree
I2CWrite SDA,SCL,I2CDevice,[DC,$AF]'Display On
pause 10
'===============================================================================
GOSUB CLEAR_LCD
pause 500
GOSUB TITLE


MAIN:

'gosub FILL_LINE
'pause 1000
'gosub CLEAR_LCD
'pause 1000

GOTO MAIN

'======================Send data===============================================
SEND_DATA:
DC=$40
I2CWrite SDA,SCL,I2CDevice,[DC,LCD_DATA]
RETURN
'===============================================================================
'======================Send Command=============================================
SEND_COMMAND:
DC=$80
I2CWrite SDA,SCL,I2CDevice,[DC,COM]
RETURN
'===============================================================================

'==============================clear lcd========================================
CLEAR_LCD:
X=0
Y=0
LCD_DATA=$00
'Send 0 to every column in every line
FOR Y=0 TO 7
    gosub SET_XY
    FOR I=0 TO 127
        GOSUB SEND_DATA
    NEXT I
NEXT Y                             
RETURN 

'=============================FILL_LINE=========================================
FILL_LINE:
X=0
Y=4  'I choose 4.th line to blink
LCD_DATA=$FF ' Every line contains pixels $01 is bottom pixel, $80 is top pixel
    gosub SET_XY
    FOR I=0 TO 127
        GOSUB SEND_DATA
    NEXT I                         
RETURN
'===============================================================================

'===========================================SET X AND Y=========================
SET_XY:
COM=$21:GOSUB SEND_COMMAND
COM=X:GOSUB SEND_COMMAND
COM=127:GOSUB SEND_COMMAND
'Above 3 lines means; Column starts at X and End at 127
COM=$22:GOSUB SEND_COMMAND
COM=Y:GOSUB SEND_COMMAND
COM=Y:GOSUB SEND_COMMAND
'Above 3 lines means; Line starts at Y and end at Y, 
'which means ; Only work on specified line!
RETURN
'===============================================================================
END