sketches will not upload to board

several years ago got uno, worked fine our windows computer. now, using on macbook air, had stuck uploading without stop. tried install drivers because thought might help. don't remember if worked once afterwards , stopped or not, never upload. far can tell, i've removed drivers, still not upload sketches.
here error.

arduino: 1.8.5 (mac os x), board: "arduino/genuino uno"

archiving built core (caching) in: /var/folders/22/b38pk7bj78z1tmybq65dg4x80000gn/t/arduino_cache_350576/core/core_arduino_avr_uno_1910dc4c15bc5d5c82673360f14ded58.a
sketch uses 928 bytes (2%) of program storage space. maximum 32256 bytes.
global variables use 9 bytes (0%) of dynamic memory, leaving 2039 bytes local variables. maximum 2048 bytes.
/users/ziadk/desktop/arduino.app/contents/java/hardware/tools/avr/bin/avrdude -c/users/ziadk/desktop/arduino.app/contents/java/hardware/tools/avr/etc/avrdude.conf -v -patmega328p -carduino -p/dev/cu.usbmodem1411 -b115200 -d -uflash:w:/var/folders/22/b38pk7bj78z1tmybq65dg4x80000gn/t/arduino_build_805633/blink.ino.hex:i

avrdude: version 6.3, compiled on jan 17 2017 @ 12:01:35
         copyright (c) 2000-2005 brian dean, http://www.bdmicro.com/
         copyright (c) 2007-2014 joerg wunsch

         system wide configuration file "/users/ziadk/desktop/arduino.app/contents/java/hardware/tools/avr/etc/avrdude.conf"
         user configuration file "/users/ziadk/.avrduderc"
         user configuration file not exist or not regular file, skipping

         using port                    : /dev/cu.usbmodem1411
         using programmer              : arduino
         overriding baud rate          : 115200
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x00

avrdude done.  thank you.

an error occurred while uploading sketch

this report have more information with
"show verbose output during compilation"
option enabled in file -> preferences.

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