If front panel audio jack is bad you can unplug the audio port plug to the front panel and the system wont sense the loopback of this as a valid audio port maybe. Some of the audio port connections have a single wire that acts as a loop back for the system to know that there is a audio jack connected at the other end of the connection and unplugging it may be the cure and then just use the rear audio jack. If the audio jack is the one that is in the rear that is damaged that is integrated to the main board then the only option is to replace the main board or use one of those USB stick audio cards ( or ) install a sound card and have that set as the connection that you want if a PCI Express slot is available to taking a sound card which then bypasses the integrated sound.