When I Woke up

When i Woke up this morning, After putting my computer to sleep the night before. All my applications are refreshed, like im opening them for the first time. How could this be? Ive had my computer for 1 month and i know ive been inside these apps like iphoto, mail, and everything else. ALso i lost 3 apps i downloaded from the app store. Really pist bascially, My nephews slept over the night before but they dont kno my password to get in my computer? So someone please explain to me what happened? Has anyone had this happen to them. Bullying is not ok Apple!