HDD detection

Yesterday I was defragmenting my HDD for the first time and after it was finished I decided to restart my PC. When it restarted a message during boot appeared that it was still defragmenting and after it finished my PC booted up but my HDD was nowhere to be found either on disk management or...

The Issue I moved my computer from one desk to another around a week ago, and since then it has begun restarting every so often, though after the initial restart it will do so more frequently unless turned off for a while. For detail, these "restarts" don't fully restart the system itself...