Database refresh

hello,
this is my first blog entry here,
instalation works fine and also the first weeks all runs propably, but since a few weeks, no media files could be found any more,
log file posts error messages like:
my idea was to clean up the database? But I don't know why?
I try to delete the entry in the libaray, say refresh and add again, with no result.
maybe is there a posibility to make a "hard" cleanup from the database?
With best regards from germany
Michael
this is my first blog entry here,
instalation works fine and also the first weeks all runs propably, but since a few weeks, no media files could be found any more,
log file posts error messages like:
2013-12-31 11:53:42,916 DEBUG [PlaylistMaintainerThread] Item '/home/music/MP3/Dieter Thomas Kuhn/Musik ist Trumpf/06 Dschinghis Khan.mp3' cannot be resolved to an entity in the Serviio library, will try again later
my idea was to clean up the database? But I don't know why?
I try to delete the entry in the libaray, say refresh and add again, with no result.
maybe is there a posibility to make a "hard" cleanup from the database?
With best regards from germany
Michael