Can I replace a broken USB front port??

Yes you can and there are some that can be mounted in 5" bay but get the 8-in-1 media readers for more features. The are also some external usb ports. But replacing the stock mounted usb port, well that would require you some screwing, but it depends on your system. Try ebay for the same model as some are selling computer scrap like empty cases. You can also get them at Newegg and other online stores.