WordPress database error … for no reason?

I can’t access the comments in all of my blogs suddenly. I see this error:

WordPress database error: [Can’t open file: ‘wp_comments.MYI’ (errno: 144)]
SELECT * FROM wp_comments WHERE comment_post_ID = ‘154’ AND comment_approved = ‘1’ ORDER BY comment_date

It was still doing fine 1.5 hours ago when I received my latest comment (I know because the comment was emailed to me).

Between then and now, I haven’t touched anything… in fact I just got home. And in fact, I haven’t messed with my host server or with WP for ages.

Can someone please help? My site is at http://www.sheylara.com