Diode identification and possible substitute HELP

Thanks to your excellent photo it's obviously a reverse protection diode, and has been blown by the power been connected the wrong way round - simply removing it should make it work again, but obviously removes the protection. That would be the first thing to do - being VERY, VERY careful not to connect the power the wrong way. Once you've proved it still works, then you could (and should) replace the diode - it's not at all critical, any similar shape and size silicon diode should be fine, something around 2A perhaps?.