[Mechanic mad]

Hi guys I've joined this as a last resort as I really am lost with my buggy now, it was turning over and starting regularly when I needed it to and I came to it one afternoon after I had already had it running earlier in the day and suddenly when I turned the key nothing happened not even a click, I've changed the solenoid, checked the fuse (as its an obvious) and also stripped and cleaned the starter motor oh and also checked and changed battery's! And well still nothing. Any thoughts would be greatly appreciated

Thanks