Perhaps the setting is important because there *is* no setting?
Anyone can be in disgrace with fortune and men's eyes, anywhere. It's a universal. He may not be the first to fall (Adam and Eve) but when he falls, he feels abandoned by God and man. It may be that the emotional cost is more important than the physical loss, and that by eliminating references to any distinct or recognizable place, the persona is able to focus more intensely on the emotional.
It is an emotional problem that the speaker faces, after all: he's envious. He wants to be like anyone else but himself. He's depressed and irritated; he almost loathes himself. To carry on with sullymonster's interpretation, he has utterly fallen from grace, and not just God's grace, or man's, but his own as well. He's lost his power and position in the world, but more to the point, he's lost his confidence, his self-esteem.
This graceless state can be changed, however, when he thinks on his love, an emotional rather than a physical move. Alone, he calls heaven and no one answers his "bootless cries." Thinking of her allows him to change his perception of his circumstances and to be like the lark who sings hymns to heaven's gate. This elevates his mind and distances him from the unpleasantness in his situation, whatever that is.
The cure is not physical. It is not a return to better circumstance, nor is it a gain in material wealth. Instead, it is a shift in consciousness brought about by a recollection of love. Could be that the setting isn't important because the crux of the problem is internal.