The memory got used upto 7.02Gb of 8GB available,so I reset phone via the option available in Settings>About,After the reset,touch settings available in the settings>Extras & Info are missing .Also the brightness control level has also been missing.I cant even rollback to Windows Phone 8.1 ,because on connecting the device to Laptop,following error is raised "USB Device Not Recognized".What should i do now ?