Hi, I was following the instructions of holding down command+R and got to MAC OS Utilities screen. I erased the hard drives and I didn't realise at that point that I had to reinstall the OS system from the previous menu. I just shut it down and then when I turned it back on I got the following screen.
It then said downloading from the web and showed another screen but I don't have an image of this as it won't appear anymore.
Then it went through to this screen and it doesn't do anything else. I have left it for a few hours and nothing changed so I thought I would seek advice:
21.5-inch, Mid 2010
Processor 3.06 GHz Intel Core i3
Memory 4 GB 1333 MHz DDR3
Graphics ATI Radeon HD 4670 256 MB
Serial Number W8044AQ7DAS
Software OS X 10.9.5 (13F1911)
[Jack Stewart]"It then said downloading from the web and showed another screen but I don't have an image of this as it won't appear anymore."
That it actually one of the most amazing things about the Mac that Windows has never learned to do... If a Mac sees a blank hard drive, it will happily download the version of macOS that it originally came with from Apple's servers. This is probably what was happening during this time.
What if you use Command (⌘)+R again to get back to the Recovery partition and re-install macOS from there?