Arduino Mega no more detected when plugged

Hi all,

I need some help. I’m using Linux and I have a Arduino Mega witch was working fine, but not anymore.
When I plug it to my computer, it not detected, but is used to be…
Is there any other way to send my knew sketches?
I tried with a Uno without chips, but doesn’t work. I also try to burn a new bootloader, without success…
Please, any help or suggestion is welcome!!