Have you jailbreaked your device before?and you ask siri to launch cydia app and suddenly all your apps cannot be launched through siri?i have this same kind of problem but now it is solved.First you need to go into iFileand find these 2 files/var/mobile/Library/Caches/com.apple.LaunchServices-045.csstore /var/mobile/Library/Caches/com.apple.mobile.installation.plist
Once you find them don't delete them just in case change them to /var/mobile/Library/Caches/com.apple.LaunchServices-045.csstore.bak /var/mobile/Library/Caches/com.apple.mobile.installation.plist.bak
This basically renders them invisible, you can go and delete them later, always good to keep a backup
Once you have changed the name back out to Springboard and do a full reboot. Upon reboot you will notice all your stock apps are there and your installed cydia apps but NO appstore apps. DONT PANIC
Just sit back and chill as iOS will slowly rebuild your apps on the springboard. I have over 300 apps on mine so it took a couple of minutes. Once all your apps are showing give Siri a test.. Should work perfect.
Then go back into iFileand removed the filesyou changed to .bak
Done.. lemmie know how you go