Boot Failure

Recently, when I startup my computer suddently my computer can not load into windows and just stop in Dos Screen showing message “Boot Failure, insert system disk, press enter” and also I try to detect my hard disk in Bios but cann’t detect it and when sometimes I startup my computer, it is works well.Is the power cable attached to the hard disk problem or anything problem??I don’t know!Is any person can help or explain to me what exactly happen to my PC as soon as possible?
Thank You!