I don't know who started this thread but this is confusing. If you did not
start it then start your own, as hijacking a thread is a federal offence and
highly frowned upon. ;)

To fix your problem install ubuntu-restricted-extras in Synaptic (system,
Administration in menu). Just search for restricted (not quick search). That
will allow you to play mp3s, use flash and play videos. While there install
vlc, too.

To view lit files install calibre (also with Synaptic, in fact use it for
all of your installations.)

I have not used a modem in well over ten years, so can't help you there.