Loop Back test failed


I just did the loopback test, because I had some issues with my Arduino Uno board. When I tried to upload a sketch the ON light goes on, the RX and L lights blink, but the TX light would never blink. I get this error:

avrdude: stk500_recv(): programmer is not responding

However the computer can see my arduino in the ports (COM4). My Arduino was just working fine, but I tried to upload a new sketch and all of a sudden it gave me errors like this.

The loopback test gave me a fail. It didnt echo the input that was I was typing in the Serial Monitor. So I assume that the USB to serial converter is broken, but how do I fix this. I have spend hours on youtube and forums so far.

Please let me know.