"Cannot find symbol" Compiling Error

Hey, so I was making my mod, and I have been for about a month now, and everything was running perfectly smoothly. However, I log in one day, and now whenever I save something, it tags everything in my mod as a compiling error. The Gradle says that it "cannot find symbol".

Here's an example of one of my elements:

symbol:   class DirectionProperty 
  location: class CrackedBluestoneBricksBlock 
C:\Users\cocoa\OneDrive\Documents\Simple Mining\simple_mining\src\main\java\net\mcreator\simplemining\block\CrackedBluestoneBricksBlock.java:18: error: cannot find symbol 
   public int getLightBlock(BlockState state, BlockGetter worldIn, BlockPos pos) { 
                            ^ 
  symbol:   class BlockState 
  location: class CrackedBluestoneBricksBlock 
C:\Users\cocoa\OneDrive\Documents\Simple Mining\simple_mining\src\main\java\net\mcreator\simplemining\block\CrackedBluestoneBricksBlock.java:18: error: cannot find symbol 
   public int getLightBlock(BlockState state, BlockGetter worldIn, BlockPos pos) { 
                                              ^ 
  symbol:   class BlockGetter 
  location: class CrackedBluestoneBricksBlock 
C:\Users\cocoa\OneDrive\Documents\Simple Mining\simple_mining\src\main\java\net\mcreator\simplemining\block\CrackedBluestoneBricksBlock.java:18: error: cannot find symbol 
   public int getLightBlock(BlockState state, BlockGetter worldIn, BlockPos pos) { 
                                                                   ^ 
  symbol:   class BlockPos 
  location: class CrackedBluestoneBricksBlock 
C:\Users\cocoa\OneDrive\Documents\Simple Mining\simple_mining\src\main\java\net\mcreator\simplemining\block\CrackedBluestoneBricksBlock.java:23: error: package StateDefinition does not exist 
   protected void createBlockStateDefinition(StateDefinition.Builder<Block, BlockState> builder) { 
                                                            ^ 

There's twice this amount of errors for this one item.

This is just one item, and it does this for every single item I've made (which is a lot)
Can anybody help fix this?