Critical files are overwritten, data is irreversibly changed or lost when mods are removed, game-saves are ruined...

Many many mods will break your game when you install them incorrectly or uninstall them and it is suggested you back up your gamesaves and /data/ folder before overwritting anything that is original to the game.
If you do not many times your only options are re installing the entirety of Skyrim's data or making an entire new save.

You will receive no sympathy when there is no other solution and your threads will be closed.
Thank you for your time and attention.