My dog has been licking himself on the inside of his thighs and around his genitals and it has turned his fur a ginger colour (he's a pale coloured dog).

Is there anything I can get that will clean the fur to it's original colour?  I thought there may be a cleaner that's used to get tear stains off white dogs that might work?

Any suggestions?

Bathing with a solution of bicarbonate of soda is effective - but you need to find out the reason for him licking, because until that stops the staining will return immediately.