You can be disheveled without ever being “sheveled.” It's pronounced /di-SHEH-vuhld/, not as you sometimes hear it, /dis-HEH-vuhld/.

Can disheveled be used as a verb?

verb (used with object), di·shev·eled, di·shev·el·ing or (especially British) di·shev·elled, di·shev·el·ling. to let down, as hair, or wear or let hang in loose disorder, as clothing. to cause untidiness and disarray in: The wind disheveled the papers on the desk.

What do you call words that are not words?

Also called pseudowords, non-words can sometimes sound like a whole lot of jabberwocky. Then again, you might catch yourself using some of these words in everyday speech. They're nonstandard at best and totally wrong at worst.