Please help- LG Smartworld app won't RE-install?

[alackthereof]

I successfully downloaded and installed the apk for the smartworld app the first day I got the g3. Then a couple days ago, the LG smartclean feature deleted the app since I hadn't used it in over a week (I've since changed the settings) and now I cant get the apk to install again. on the screen where it asks me if i want to install or cancel, I cannot press the install button.

I've seen other people have problems where they cannot access the install button but I do not have any kind of screen dimming or screen filtering app on my phone that could be blocking it. Has anyone had this issue or do they have any tricks to get back apps that were accidentally deleted and didnt come from the google play store??

Any advice is greatly appreciated!