A bunch of apps have disappeared when i turned on my phone, is it possible to get them back?

[AC Question]

I took my phone out of my pocket and it was saying Android searching for apps and the phone switched off and the phone switched back on and all of a sudden I could recognise that there was apps missing so I turn the phone off again and restarted it and they were still apps missing what should I do?

 

[anon(632115)]

Where were these apps? Internal memory or SD card?