A literal answer - Desolder the resistor - determine the resistance value - take it to an electronics hobby store and buy one of the same resistance and wattage. Solder it back in.
The resistor that worries you will either be open circuit - or short circuit (very rare). It may be that it has just become blackened over time by excessive heat - the designer specified too low a wattage - or production made a bad substitute. It is sometimes hard to find the value on a blackened resistor - the bands or writing can't be seen well. A blackened resistor is not necessarily broken - sometimes they still work fine - just hot.
If the resistor has failed it will have failed either because it was poorly made or because an external fault caused it. If a fault on the board is "cooking" the resistor then any replacement resistor will be likely to fail too.
Good luck...
Peccavi, March 2010
