As you can see, I am unable to view any sort of text inside the TMP. It was working perfectly fine until yesterday. Also, all my Layers are visible in the settings. Any ideas on how to fix this?

Either drag and drop a TMP_Font asset from your editor, or click on the little target symbol which will bring up an editor window of all types TMP_Font, then assign one of the fonts that pop up. If you are still having issues after assigning a font let me know.