Did it take you one week to gain all of the weight you want to lose? No
Consequently, it's going to take a lot longer than a week to lose that weight.
Some people lose 10 pounds in the first week while other people, like you, don't lose a single pound. In either situation, it means almost nothing.
In the first week people begin a diet, most people begin to retain less water, have less food in their digestive system, and with a low carb diet they will likely begin to deplete their glycogen stores. When you combine all of those together, it could easily yield more than 10 pounds lost. HOWEVER, that doesn't mean they've lost even an ounce of fat.
In contrast, if you've just started working out, have increased your intake of red meat, and increased your sodium intake those may cause you to retain more water as your creatine levels increase (not to be confused with creatinine). You may have lost a whole pound of fat, but if you're retaining 1 pound of water, the scale isn't going to move.
Bottom line- the scale is ONE measurement, but it's not the ONLY measurement. "Losing weight" is useless if you're not losing fat which is why it's important to consider other measurements (body fat, how your clothes fit, etc).