Writer's Block

Why can't I think of something to write? I've been at it day and night, But nothing really comes to mind. The Muse of late's been most unkind In leaving me in this irksome plight. In my day, it was all so right. Fifty sonnets in just one night! Acrostics and lim'ricks and ballads refined When I could think of something to write. But now the Muse has taken flight, And what comes to mind is all but trite. I'm at a loss of words I find And cannot write what's been assigned. But it's getting late, so I best say goodnight. Why can't I think of something to write?