Hey guys, help! Basically, I'm trying to restore my old hard drive by disk utility? The

So, I've been trying to restore my hard drive in disk utility? I copied over my old MACHD to my external drive. Anyway I click on restore on the now untitled MACHD then go to my image being the '.dmg' I i saved on my external hard drive, then destination to my unnaned MACHD after about 3 hours of working it didn't do anything? It just said finished the 'blocks' so I'm trying it again In recovery mode this time rather than when I'm MAC has actually loaded up... Can anyone tell Me what else to do if it doesn't work?