What can I do to install OS in a new ssd,when the previous one is fried with no recovery?

The machine is an imac 21.5 mid 2010. Initially I tried using a bootable usb containing El capitan, it comes up in the boot menu but only loads 3/4 before displaying the no symbol ( / ). I have 4 various hard drives, 2 ssd and 2 hdd that are formatted to windows, but are functional. Nothing works. I tried making a bootable from the apple licensed "El capitan.app" and also from another source as a .dmg file. I'm using my windows pc to attempt to trouble shoot but it's becoming a head ache. I'm going to try to load a bootable "unlocked" snow Leopard, which is what it was packaged with. Until I get a good answer or order a disk I'll keep trying.