The reason why your model, texture, or material is purple or pink is that Blender is trying to find a missing file. Either the file has been moved to another folder or it has been deleted.
My model, texture, or material is purple/pink
This means you have a shader or material that uses an image file on your computer that cannot be found. Maybe you downloaded a set of PBR textures to a temporary folder and when you restarted your computer they were automatically deleted.
My whole scene is purple/pink
This means you are using an HDRI that cannot be found. Make sure the HDRI still exists in the same folder or that it hasn’t been deleted.
How to find missing files in Blender
If you know you didn’t put your textures or HDRIs in a temp folder, you could use the “Find Missing Files” feature in Blender. To access it go to File > External Data > Find Missing Files. You’ll get a new window where you will have to choose a folder to search through. If you completely forgot about the location, you could start a search that goes through your whole drive, but keep in mind that this will take a lot of time.
To avoid situations like this in the future, I can really recommend getting yourself an SSD that’s purely for your 3D work. Make it a habit to download all assets into a folder here, and save your renders, project files, and everything else here too. You will never have to look for missing files again.