You should try this tool, its really best thing to repair any mess you get yourself with your system.
I was messing with mime directory /usr/share/mime ,so i remove it, and then i discovered kalarm stopped working, it was crashing, i spent some hours trying to figure it out what was happening with akonadi-kalarm service (at first i thought it might be some upgrade), so i tried a lot of things, i searched on internet and i didint find any solution, then i try to apply a btrfs snaphot and then restored a home backup to check if i could recover all my akonadi modules working (kmail database, kalarm, etc), it didnt work.
Finally i thought it could have something to be with the mime folder i removed, so, i applyed debsums to my system and it reported me some few packages whose mime file was missing, i reinstalled all of them and the problem was fixed.
i love this tool, you'll never need again to reinstall a fresh system installation!
, it will keep fresh and clean with debsums..