It is well known that Samsung doesn't release official changelogs, mainly because Samsung doesn't give a shit about you or me.
Open up File Explorer and hit menu, select "Preferences"
Change the home folder to "/" (make sure "read root" is selected)
Restart the app
You should now be presented with a list of the phone's root folders, just select emmc and your...
That's a pretty bad mistake... The only way you could possibly recover it is if you buy a USB Jig and give that a try. Otherwise I'm afraid your up shit creek without a paddle. :(
Then I'm afraid not, you need the Sense 3.0 resource/framework files to use the widget. :(
Sounds like a hard brick, there isn't a way to recover it. Out of interest what software did you flash? Was it just a wrong package or was it software that was designed for a different phone? There might be a minor chance of recovery depending on ...