I've been in the same office location for ten years. Well it's def. time to replace the carpet, because it's worn out. I've shampooed it a thousand times, but that doesn't help anymore.
Is my landlord responsible for replacing this carpet after a certain number of years?
You can ask him to replace it and see what he says. After 10 years he should do some preventative maintanence to keep the property nice looking. If he won't then consider moving after your lease is up. If you have been a good tenant see if he will do it. Or if you want to replace it ask him to give you a credit on your rent.