Id like to use stackexchange from any app available in the market,the browser kills me when searching sites.
An official Android version has recently been released http://blog.stackoverflow.com/2014/01/stack-exchange-for-android-is-here/. An iOS version is in the works, but unfortunately no word on a Windows Phone version.
The answer is Yes. And here is one you can use. Not officially created nor has a title of StackExchange but it does possesses all the features you'll need. I'm using it and very happy with that. Please have a look.
Yup there is! But the thing is its a WebApp.
There isn't an official one so NO is the answer. But one or 2 people have wrapped the mobile web app and published but this is same as visiting stack overflow on you mobile browser.
I know that this is a WP [meta] site, but there is now a SE iOS app. Yesterday, on a whim, I had the same question, as the OP, myself and searched the AppStore. To my surprise I found one. I downloaded it, and it is very good.
There is one app, still not an official app, but it has a very good user interface, designed using the Windows 10 design language. Its called Stackie
All StackExchange sites are available. Scroll down the
Pin a Site modal to reveal and pin your favorite Stack Sites.