Hello,
I saw strangely file on my computer located in D:\Device\HarddiskVolume1\Boot and named BCD. It got no extension so I dont know what file it is. Is it virus? Or it useless file that can be deleted?
Here is a post describing what BCD is (normally !). In your case, no doubt your knowedge of the history of your PC will help you determine why it appears on your D:\ drive and not C: