Arduino was working but now not uploading

Hi All,
is there a method to hard reset or check the bootloader is healthy? My genuine leonardo is pretty new, it was working fine but now it won't accept uploads, it goes to ~90% and sits for ages doen't matter what sketch I use.
I have obviously tried the well advertised checks and tests so I'd assume what I really need is to get the bootloader reset/checked - any ideas would be welcome.

Shows you up any error? If yes, post it, to understand the problem deeper!

yer the error is buy a BTW arduino rubbish, binit buying a decent board like the raspberry or beagle bone

manicmarauder:
yer the error is buy a BTW arduino rubbish, binit buying a decent board like the raspberry or beagle bone

Great idea

Enable verbose upload, post the error here