example Blink does not compile

Arduino Basic example “Blink” produces the following compiler error message:

Arduino: 1.0.6 (Windows 7), Board: “Arduino Uno”
C:\Program Files (x86)\Arduino\hardware\tools\avr\bin\avr-g++ -c -g -Os -Wall -fno-exceptions -ffunction-sections -fdata-sections -mmcu=atmega328p -DF_CPU=16000000L -MMD -DUSB_VID=null -DUSB_PID=null -DARDUINO=106 -IC:\Users\Sam\Documents\Arduino\hardware\arduino\cores\arduino C:\Users\Sam\AppData\Local\Temp\build3251653724339215887.tmp\Blink.cpp -o C:\Users\Sam\AppData\Local\Temp\build3251653724339215887.tmp\Blink.cpp.o

Blink.ino:18:21: error: Arduino.h: No such file or directory
Blink.ino: In function ‘void setup()’:
Blink:20: error: ‘OUTPUT’ was not declared in this scope
Blink:20: error: ‘pinMode’ was not declared in this scope
Blink.ino: In function ‘void loop()’:
Blink:25: error: ‘HIGH’ was not declared in this scope
Blink:25: error: ‘digitalWrite’ was not declared in this scope
Blink:26: error: ‘delay’ was not declared in this scope
Blink:27: error: ‘LOW’ was not declared in this scope

sounds like something went wrong during install.
Is it your first code you compile?

No, it is not the first. I get strange compile errors even on old programs that have run for years.

seems your Arduino.h got corrupted, you should check if it is still there

path should be something like

C:\Program Files (x86)\arduino-1.0.6\hardware\arduino\cores\arduino\arduino.h

Thank you. I got it fixed by eliminating all extraneous folders named arduino, uninstalling, and doing a fresh install.