itunes, causing me to lose alot of songs out of my playlist? songs vanish.

itunes 64 bit causing me to lose alot of songs out of my playlist, songs vanish. this is not the first time but many times I have had to start over.I uninstalled itunes thinking that it would help to reboot it fresh, room on my hard drive is not a problem, I am very disappointed with the way itunes handles problems they try to sell yoou back the very music you worked long and hard for.