All my music disappeared

Hi there, I haven't updated the system or anything like this but this morning realised my Music won't find out any music from David Bowie. Then I found there are large chunks of my music catalog missing all together, basically all my music which I manually transferred from old cds, etc. stored on my mac for over the last 13-14 years, excluding few tracks I bought via Apple. I tried to tuned in with iCloud but all that happened afterwards was that the very few songs left on my Music disappeared, too. Any suggestions?