Getting content mismatch error

Hi all, I'm new to arduino and I just got a mega2560 and my computer is running OSX 10.10. I first tried a few basic codes, such as a blinking led on a breadboard. It worked perfectly. I just tried to upload another simple code, and it is giving me this error code:

avrdude: verification error, first mismatch at byte 0x0000
        0x14 != 0x06
avrdude: verification error; content mismatch

Does anyone know how to solve this? All help is much appreciated

Please post the sketch you are trying to upload. Also let the forum members know if you are able to upload the blink sketch again and are only having problems uploading a particular sketch.