i mean, setCursor(50,0) that means, its the 51th (virtual) block
Have you followed the link I provided in reply #5 so that you might possibly let us know what you mean by the 51st virtual block in terms of something that relates to an actual display controller?
The way I interpret things this would be DDRAM location 0x4A which is located near the right center of the second row of a 16x2 display, at position (10,1).
Here is how I to do it in assembly language, which is the technique that I prefer to use. If you use some other method then you will have to reveal what it is, something that you seem reluctant to do.
ldi temp, 0x4A ; desired DDRAM address
ori temp, 0b10000000 ; convert the plain address to an address instruction
call lcd_write_instruction
ldi temp, 80 ; data sheet calls for a delay of at least 40 uS
call delayTx1uS
Don