Error but it doesn't tell me anything I understand

C:\Users((MY USER NAME))\AppData\Local\Temp\ccLILiQ6.ltrans0.ltrans.o: In function main': C:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino/main.cpp:46: undefined reference toloop' collect2.exe: error: ld returned 1 exit status exit status 1 Błąd kompilacji dla płytki Arduino Leonardo.

The last line is Polish and translates to something like:Compilation error for arduino leonardo board.\

I reinstalled the IDE and it still pops up. Any ideas how to fix it?

The error indicates that your sketch does not contain a loop() function. If you think it does, post your code.