EVERYTHING seems to have stopped working....

I have developed several issues simultaneously, by the looks of things; I satarted getting messages saying that "boards.txt" was missing, THEN my boards manager just lost my mkr wifi 1010 option under "tools", despite acknowledging that it was still installed(and refusing to allow me to REMOVE, DOWNGRADE or REINSTALL it....), and now my IDE just REFUSES to compile or upload anything, even a blank sketch, to ANY of my boards (I have a couple of UNOs, three NANOs, and a MKR WiFi 1010, if it helps.....?)

I have included my latest error message as hopefully some sort of insight or clue as to the source of my woes....?

someone pleaseplease rescue me here!!

Arduino: 1.8.10 (Windows 7), Board: "Arduino Uno"

D:\ARDUINO\ide\Arduino\arduino-builder -dump-prefs -logger=machine -hardware D:\ARDUINO\ide\Arduino\hardware -hardware C:\Users\Nav\AppData\Local\Arduino15\packages -tools D:\ARDUINO\ide\Arduino\tools-builder -tools D:\ARDUINO\ide\Arduino\hardware\tools\avr -tools C:\Users\Nav\AppData\Local\Arduino15\packages -built-in-libraries D:\ARDUINO\ide\Arduino\libraries -libraries D:\ARDUINO\ide\sketchbook\libraries -fqbn=arduino:samd:uno -vid-pid=1A86_7523 -ide-version=10810 -build-path C:\Users\Nav\AppData\Local\Temp\arduino_build_44763 -warnings=default -build-cache C:\Users\Nav\AppData\Local\Temp\arduino_cache_535619 -prefs=build.warn_data_percentage=75 -prefs=runtime.tools.arduinoOTA.path=C:\Users\Nav\AppData\Local\Arduino15\packages\arduino\tools\arduinoOTA\1.2.1 -prefs=runtime.tools.arduinoOTA-1.2.1.path=C:\Users\Nav\AppData\Local\Arduino15\packages\arduino\tools\arduinoOTA\1.2.1 -verbose C:\Users\Nav\AppData\Local\Temp\untitled1260009614.tmp\sketch_nov21a\sketch_nov21a.ino
D:\ARDUINO\ide\Arduino\arduino-builder -compile -logger=machine -hardware D:\ARDUINO\ide\Arduino\hardware -hardware C:\Users\Nav\AppData\Local\Arduino15\packages -tools D:\ARDUINO\ide\Arduino\tools-builder -tools D:\ARDUINO\ide\Arduino\hardware\tools\avr -tools C:\Users\Nav\AppData\Local\Arduino15\packages -built-in-libraries D:\ARDUINO\ide\Arduino\libraries -libraries D:\ARDUINO\ide\sketchbook\libraries -fqbn=arduino:samd:uno -vid-pid=1A86_7523 -ide-version=10810 -build-path C:\Users\Nav\AppData\Local\Temp\arduino_build_44763 -warnings=default -build-cache C:\Users\Nav\AppData\Local\Temp\arduino_cache_535619 -prefs=build.warn_data_percentage=75 -prefs=runtime.tools.arduinoOTA.path=C:\Users\Nav\AppData\Local\Arduino15\packages\arduino\tools\arduinoOTA\1.2.1 -prefs=runtime.tools.arduinoOTA-1.2.1.path=C:\Users\Nav\AppData\Local\Arduino15\packages\arduino\tools\arduinoOTA\1.2.1 -verbose C:\Users\Nav\AppData\Local\Temp\untitled1260009614.tmp\sketch_nov21a\sketch_nov21a.ino
Using board 'uno' from platform in folder: C:\Users\Nav\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.4
Using core 'arduino' from platform in folder: C:\Users\Nav\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.4
Detecting libraries used...
recipe.preproc.macros pattern is missing

Error compiling for board Arduino/Genuino Uno.
java.lang.NullPointerException
java.lang.RuntimeException: java.lang.NullPointerException
at cc.arduino.contributions.packages.ui.ContributionManagerUI.lambda$onInstallPressed$2(ContributionManagerUI.java:175)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
at cc.arduino.contributions.packages.ContributionInstaller.remove(ContributionInstaller.java:276)
at cc.arduino.contributions.packages.ui.ContributionManagerUI.lambda$onInstallPressed$2(ContributionManagerUI.java:170)
... 1 more

Dear lord, what did you do?! I am not sure what you did to the samd core, but you appear to have convinced the ide that it should be building all boards as if they were SAM devices (even avr's like uno/nano), using the (hosed) core...

But in any event, uninstall ide, delete c:/users/nav/AppData/local/Arduino15 (note, AppData folder is hidden), reinstall the ide, and you're good to go. You may not even need to uninstall/reinstall, though with the amount of effort involved to break the ide in the way you have, I have no faith that you havent also trashed something there too.

Don't go fiddling with board packages installed by board manager, or anything else under that arduino15 folder, unless you really know what you're doing.

If you have been fiddling with the IDE I have attached some clean up instructions that may help you get back on track.

Bob.

CLEAN UP BEFORE INSTALLING ANOTHER COPY OF THE IDE OR ARDUINO CREATE.pdf (347 KB)