I changed the ip address of the 'A' record of domain aarkt.com by mistake and the site has vanished

If you have AWS Config switched on you should be able to see the change there as Route 53 resources are supported. Otherwise is the web server for aarkt.com in once of your AWS accounts? You could look into resources there. Apart from that try googling "dns history" - I've never been down this path but it looks like there might be some options for exploring previous settings.