Netgear WGR614 router port 3 stopped working after cable installation

Hi: My cable modem, Netgear WGR614 router, two hardwired desktop computers, and wireless laptop were all working well as a system, until I changed a cable on port 3 (going from router to desktop computer). I was using a reliable 14' Cat5e cable, but wanted to test a new 25' one that I just bought. This newer cable is a Belkin SNGLS FASTCAT5e Patch CBL, 4PAIR;RJ45M/M. After plugging in the new 25' cable, after turning everything off, I got no connection between the router and the desktop. So, I plugged back in the reliable 14' cable and still have no connection, even though I did before testing the new cable. In short, I can't get the Port 3 light to go on or get a connection with it. The vendor insists (emphasis added) the cable is okay, saying he has never had a problem with this brand and type of cable. I'm not going to test the cable in another port, because it might disable another one. So, then, I don't know how to test the new cable to see if it is okay. Also, could just adding a different cable change my software configuration somehow? I'm wishing I could restore the use of port 3. Any help would be greatly appreciated. Thanks, Gibby