Upload Fails for ALL sketches.

Hey guys. I'm having trouble. When ever I try to upload a sketch to my Uno, it spits out an error. I know it is not the USB cable, nor my computer, because when I try to upload to my Mega it is easy. I can't even get the Blink sketch onto my Uno.

I have checked hundreds of times in the Tools menu, and thus I know the Uno is selected and the port is correct. But always the same message:

Arduino: 1.6.8 (Mac OS X), Board: "Arduino/Genuino Uno"

Build options changed, rebuilding all

Sketch uses 1,066 bytes (3%) of program storage space. Maximum is 32,256 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 2,039 bytes for local variables. Maximum is 2,048 bytes.

avrdude: stk500_paged_write(): (a) protocol error, expect=0x14, resp=0x10
avrdude: stk500_cmd(): programmer is out of sync
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.

How can I fix this??? Please I need this ASAP! :o

Has it ever worked in the past?

How can I fix this???

You!!! need!!! to!!! buy!!! a!!! new!!! UNO!!!

And don't do whatever you did to fry this one again.

And stop with the stupid excess punctuation. It's annoying.

Do you have anything on pins 0 and 1? These are used by the serial port. Unplug whatever is plugged into them, and see if your sketch uploads.