No activity after a couple of week

I am brewing a wheat ale, wyeast ale yeast. This is the first time I have used wyeast.

I brewed about two weeks ago. I broke the wyeast inner package as instructed, let it sit for about a half hour and then opened and pitched.

The yeast was pitched at room temperature, with the wort at about 75 degrees. It has been two weeks, I opened the fermenting tank yesterday and saw no activity and the yeast was on the top of the wort. What can I do to start the fermentation?

What you may seen are the remains of krausen. If you a hydrometer check the gravity and tell us the result.

Blender's right, the yeast may have silently done its thing already and fermented your beer out, or it truly may not have taken off, like you said.

There's no way to tell for sure without taking a sample for your hydrometer gravity reading.

Does it smell like wort or like alcoholic beer?

I will check and post the result on her later.

It is my understanding that when fermenting a wheat ale, noticeably more krausen will be produced. Is this true or could it have fermented without showing any signs?

Usually yes but I have brewed a Honey Wheat that had very little visible krausen during fermentation, and finished in about 6 days.