Getting errors every time I try to compile any Sketch

HI, First I will tell you that I am new using the Arduino Mega 2560 and the C++ coding but am trying to learn it. I had everything installed and working so it would verify any sketch that I tried. Then I started getting some sketch failures and I probably did a dumb thing. I removed the IDE code from my windows 10 Laptop. I reloaded the IDE files but since then I get an error when I try to verify or load a sketch, even the Blink sketch. Here is an error I got when trying to verify a sketch:

Arduino: 1.8.5 (Windows 10), Board: "Arduino/Genuino Mega or Mega 2560, ATmega2560 (Mega 2560)"

c:/program files (x86)/arduino/hardware/tools/avr/bin/../lib/gcc/avr/4.9.2/../../../../avr/lib/avr6/crtatmega2560.o:(.init9+0x0): undefined reference to `main'

collect2.exe: error: ld returned 1 exit status

exit status 1
Error compiling for board Arduino/Genuino Mega or Mega 2560.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Try restarting the Arduino IDE.

Tried to reset it but didn't change. Still get the error.