What you experience is a temporary log-in with the Guest account. To switch it, press the Windows key, then click to enter Metro interface, then click on the icon next to the username (Power Options). Choose Log Off then log-in with your normal username and the files will be back as they were. Secondly, perform a scan with your AVG Antivirus because it's possible that SVChost is infected with malware. Additionally, press Windows +C > PC Settings > Update and Recovery > Recovery. Initiate the recovery process and Windows will restore everything as it was.