DUE has disappeared from list of boards/ Board manager not working?Help please!!

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

WTF

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

  • Click the link on the line following File > Preferences > More preferences can be edited directly in the file. This will open the Arduino15 (or similar name depending on OS) folder.
  • Delete all files under the Arduino15 folder except for preferences.txt. Please be very careful when deleting things from your computer. When in doubt, back up!
  • Tools > Board > Boards Manager
  • Wait for downloads to finish
  • Click "Close"

Hopefully this time when you open Boards Manager it will have no verification error. It should not be necessary to install Arduino SAM Boards since you already have it installed. You only need to open and then close Boards Manager for it to download the Arduino package index JSON file and rescan the installed hardware packages.

thank edited for that only wasted a full day edited about with it for a 30 second job

Works now THANK YOU VERY MUCH FOR YOUR HELP

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