Comment 0 for bug 1536519

# sudo apt-get install muon
The following packages have unmet dependencies:
 muon : Depends: libmuon (= 4:5.4.3-0ubuntu1~ubuntu15.10~ppa1) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

But when

sudo apt-get install libmuon=4:5.4.3-0ubuntu1~ubuntu15.10~ppa1
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
  libdiscovercommon muon-discover muon-notifier muon-updater plasma-discover plasma-discover-updater
The following NEW packages will be installed:
  libmuon
0 upgraded, 1 newly installed, 6 to remove and 1 not upgraded.

Looks like you have troubles in package dependencies.