Spelling does not work. What can I do?

There are a couple of things to try:

• Highlight all text and verify in the Inspector > Text > More, that a language is chosen.
  
• "Clean up" the document by exporting it to some other format (MS Word or old Pages formats for example), and import it again.
• Go to Applications > Utilities and run Disk Utility. Go to First Aid > Repair Disk Permissions. (It actually has worked for people with this problem.)
• You may have an old version of CocoAspell. Update to a newer version, and the problem may go away. (If you do not even have it installed, do not bother upgrading, of course.)
• Check username/Library/Services. If you see a file called "Spell Catcher Services.service", delete it, log out, and log back in.
• Check username/Library/Services. If you see a file called "aspell.service", delete it, log out, and log back in.
• Remove files from username/Library/Spelling
• Check Username/Library/Application Support. If you have a folder there called "Spell Catcher", remove it.
• Go to /Library/Caches and trash all files ending with .csstore, and then reboot.