Arduino uno Serial port 'COM3' not found.

Today after messing a bit with my arduino I decided to change some code up a bit, only to get an error Serial port 'COM3' not found did you select the right one from the Tools > Serial port menu? , and when I try to go into that Serial port menu it is grayed out.
So I decided to check if I could update the drivers...
The arduino did not even show up on device manager nor does it make a
sound when I plug it inside my computer, at first I thought it was fried but then again
I have not plugged any external power except a USB into it so I can code. It's very weird because it even has the "on" light lit...

On a side note even though all of this happened my arduino can still make my buzzer buzz through POWER 3.3V and GND

here is what I get when I try to compile and upload:

Binary sketch size: 1,096 bytes (of a 32,256 byte maximum)
processing.app.SerialNotFoundException: Serial port 'COM3' not found. Did you select the right one from the Tools > Serial Port menu?
at processing.app.Serial.(Serial.java:191)
at processing.app.Serial.(Serial.java:77)
at processing.app.debug.Uploader.flushSerialBuffer(Uploader.java:77)
at processing.app.debug.AvrdudeUploader.uploadViaBootloader(AvrdudeUploader.java:175)
at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:67)
at processing.app.Sketch.upload(Sketch.java:1671)
at processing.app.Sketch.exportApplet(Sketch.java:1627)
at processing.app.Sketch.exportApplet(Sketch.java:1599)
at processing.app.Editor$DefaultExportHandler.run(Editor.java:2380)
at java.lang.Thread.run(Thread.java:619)

Thank's! btw I heard this could be a problem with the chip 8u4 or something like that, and if you did not guess I am a newby at this, so take it easy please and thanks again!

Try a different (known to work) USB cable.

You may need to reflash the 8U2/16U2 firmware. I had to for some reason a while back and it was pretty easy

smeezekitty:
You may need to reflash the 8U2/16U2 firmware. I had to for some reason a while back and it was pretty easy

How do I actually do that? do you have any sources? thanks in advance.

http://forum.arduino.cc/index.php?topic=197246.msg1455757#msg1455757

It doesn't help that Arduino did not update the instructions for DFU programming for the UNO REV3