i decided to clear out my computer, backing up video photo and music onto a hard drive, that was fine. i managed to free about 300gb from the main drive. I then decided to defrag the computer. a little while into the defrag it decided to restart. i assumed the defrag was complete quicker than i expected, i then tried to modify startup programs but before i got into the startup tab the computer turns off and now when i turn it on again it doesnt activate the monitor, also the hdd lights dont flash and there is no beep at the beginnning like usual.