I hoplessly messed up files while downloading.

I was downloading an app from Ailurus. I decided that I did not want that app, but I would wait for it to end. A light blue dialog box had appeared with a java statement to agree to. I couldn't find a place to agree or a box to tick. But it didn't end or finish up. Sometimes a box like this seems to disappear eventually, but sometimes the dialog box is there an hour or more later. I have just cancelled out the terminal heretofore, but got locked out of synaptic and the files. Usually, just restarting the computer took care of this. But several times, I have so hopelessly messed up my files in this way, or just by mistake, or trying to agree to or get the dialogue box off that I had to re-install the whole of Ubuntu and this took quite some time.

Is there any way to correct a file when you have messed it up so badly in downloading that even "dpg --configure -a" will not correct the issue? I once did this also in downloading an update of Exaile and had to completely re-install Ubuntu, and there were other cases. Would Purge PPA work, or is there a simpler way than just re-installing every time I make a mistake in downloading? I would be most appreciative of any suggestions.

Ailurus!!!

I tried Ailurus when it first appeared. It seemed to severely mess up my sources list. It might have improved, but I would avoid it. I do not know that it installs anything then cannot be installed from somewhere else.

When the files seem to be broken, open a Terminal and try each of the following commands in turn:
sudo dpkg --configure -a
sudo apt-get -f install
sudo apt-get --fix-missing install
sudo apt-get update
sudo apt-get dist-upgrade
sudo apt-get clean
sudo apt-get autoremove
sudo apt-get update

...that might do it.

Broken Files

Thanks Alan. I have taken down your suggestion and will certainly have occasion to try it out, though I hope I don't have to use it. I am new to Ubuntu, 18 months, but my son who knows much more than I do, also warned me to be careful about such applications. Thanks again.