I already checked my port, board and processor. I used to be able to upload but after a period of time, I won't be able to upload any more. These are what are on my computer after uploading.
Arduino: 1.8.1 (Windows 8), Board: "Arduino Duemilanove or Diecimila, ATmega168"
Sketch uses 1888 bytes (13%) of program storage space. Maximum is 14336 bytes. Global variables use 55 bytes (5%) of dynamic memory, leaving 969 bytes for local variables. Maximum is 1024 bytes. avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x7f avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x7f avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x7f avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x7f avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x7f avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x7f avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x7f avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x7f avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x7f avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x7f Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.
This report would have more information with "Show verbose output during compilation" option enabled in File -> Preferences.