Video playback problems

For some reason my M8 wont play any files, this includes the one that came on the phone ever file just comes up unsupported file type.
Is there anyway to hard reset the phone without loosing all my programs and settings etc, or what other way can i fix this.
This started to happen after refreshing the video list, its on FW 9.6.3

Any help would be great thanks as i cant watch any videos