Did you store it to device or to external sd...get a a file explorer like es file explorer and use the search tool to see if you can find any of the titles on internal sd or external sd and see where they are located...when kit kat arrived I had to install power amp as suggested by another member...it found my music no matter where it was stored and played it...cloud player will find and play it also, but it uses data instead of wifi...so not always good for those who have to watch data usage.
The stock music player will not find music that is stored to external sd...so I suggest the above apps...or you could always copy and paste the music to internal sd using file explorer...that is once you find where it is.
Most common places I have found it was music folder, dcim, media, downloads.
Good luck
