Ok so i switched on the IDE just to update my 3D printer firmware witch uses an Arduino Due so i could adjust some settings 30 second job.
Now i have just wasted 4 hours trying to find what has happened to the Due board in the IDE its just disappeared. went to board manager to re-install it board manager not working
package index json file signature verification failed (in red at the botom) and only one option for AVR boards showing
tried reinstalling different IDE versions but getting the same problem
haven't touched it in 6 months was working fine last use