Welcome to this guide, which is not really a guide.
Rather, this is simply a help to reach 100% of the achievements or if you have lost your savefile.
I'm only missing one more run in my savefile to get the 10,000 doors and you have 100% of the achievements complete.

Originally posted by user:

How exactly does it work?

• you download the savefile.
  
  downloadlink [drive.google.com]
  
  
• unzip the rar file.
  
• you save your savegame in a different folder to be on the safe side.
  
  

  Originally posted by user:

  where is my savegame?

  
  
• go to C:\Users\User\Documents\Endless Dungeon\SaveFiles
  
• insert my savegame there after you have copied yours out.
  
• start your game and open a lobby, then close the game again.
  
  the game will now create a new file in your folder and you have to overwrite this name to mine. the following file is meant.
  
  
• Steam_0x01100001001b61c6_01.ctr <- this is mine
  
• now rename my file with your filename (with a similar name) and delete the new file (yours).
  
• restart the game and the save status should now have been saved.
  
  If everything works out, you will only be missing about 70-80 doors in the achievements.
  you can now start a run and get the last achievement.
  
  
  Attention. If you want to play the achievements yourself, then I would advise you not to use my savefile, as it has unlocked almost everything.
  
  I hope I could help, because it took a really long time to unlock the last 2 achievements.
  If you have any questions, please feel free to ask them in the comments or directly on my account.