Hi and welcome to the forum 
The option for tiling has not been active for a while now, it depends on the pop-shell and the integration was lacking iirc. What install medium have you used? the last ones I tried do not have the tiling option. There is a material shell option that does a form of tiling.
From the story I take it that the medium was old, and was not updated after install and the action change something, if you have backup of your data and not invested in a lot of changes it seems easier to reinstall then to troubleshoot.
If you want help with this see [HowTo] Request support
Data that would help would be:
And the output of /var/log/pacman.log would show you what the package manager has done (if anything) such as removing the software center / layout switcher.