what is happening to my save file?

every time i save my work, and close blender. when i come back later it never renders the same as when i saved and quit. what am doing wrong?

Please elaborate ?

it never renders the same as when i saved and quit.
In what way does it not render the same ? Is it different everytime or the same but not when you saved ?
Are you using keyframes, constraints etc etc ?

what am doing wrong?
Not posting a link to your blend file and not showing any screenshots !

it doesn’t render something completely different every time. it renders differently than it did at the point in which i saved it. sorry for not posting a link to my save file. not sure how, but i will try.
this is what it looked like when i saved and went to bed.


this is what it looked like when i re-opened this morning. i don’t understand i never changed a thing.

A purple colour usually means you are missing a texture in your scene whether on the object or an environment texture. Check it