Alright so this is a bit embarrassing but in the process of modding my Stardew Valley I forgot to backup the original textures along the way. I know, stupid mistake. I'd be super happy if someone could send me the original files (I need: LooseSprites, Maps, Terrain Features, and Tile Sheets.) or could direct me to a place where I could re-get them. Thanks, I'll try to be less stupid next time.
Simply right click the game in your Steam library, go to properties/local files and click on verify integrity of game cache. Steam should find the missing files and re-download them.
Don't do this, it can mess up your files that you've modded or edited. It will return to its original state so I won't recommend doing this. Just wait for a donor or download the files elsewhere.
If you do go the way of verifying the integrity, I would do it like this: Before doing it delete the files you need to have reverted back to vanilla state. Move everything that's left out of the content folder though you can leave the XACT folder if you want, makes it go faster (unless they need replaced) Verify the integrity of your files, let Steam download them. You will now have a full vanilla copy of all the files of the game, make a copy of them to keep them safe for later. Move the files you moved in step 2 back into the content folder, overwrite everything as you have deleted the files you needed fixed in step 1. Otherwise as I said earlier, I can send you whatever files you need. I have a backup of all the vanilla game files.
Do you still have a backup of the files, all I need to fix is the furniture.xnb, it's either missing or it's a bug as my TV and some items don't show.