problem on installing non play store apps manually from file manager

[arin24x7]

i've transfered an .apk (non play store app) installation file to the phone and installing it manually using a file manager, first time i've installed it successfully but now when i'm trying to re-install updated version (cracked file) at this point there is a cancel button and an install button. I've always clicked install and been fine, but from now and on, the install button is unclickable even with uninstalling the app and starting over and even now i can't install any .apk not even play store .apk manually except automatic installation from play store.
Please help. :'(

[Uliwooly]

1st keep in mind that this is NOT a warez forum

http://en.wikipedia.org/wiki/Warez

Warez are copyrighted works distributed without fees or royalties, and may be traded, in general violation of copyright law. Warez are generally unauthorized releases by organized groups, as opposed to file sharing between friends or large groups of people with similar interest using a darknet. Warez are not usually commercial software counterfeiting. Warez was initially coined by members of the various computer underground circles, but has since become commonplace among Internet users and the mass media.

[Uliwooly]

You could boot on safe mode and try again (to uninstall the apps)

http://talk.sonymobile.com/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008#U348008

[Thommo]

It's probably an app that needs to be installed via a recovery but what would I know