Flat Tire Not Taking

This is my second flat in 2 months. I went out of town for business. Fine when I left. Went I came back to the house, the front tire was flat.

Bike was sitting for about a week and a half. I tried putting air in and it won't even take air. Temperatures in South Florida have been really crazy lately so maybe that has an effect on it.

I'm guessing it's a bad air stem value?

I haven't enough time to get around to changing it...

Sorry for newbie questions.

I appreciate any help I can get. Thanks

You may have some dirt or crap in the stem, just get a valve stem cap with a remover and change it first, if it takes air, just put a touch of spit on the stem and see if it bubbles, it may even be loose, first place I would check, cheer`s