We do not see our signs;
there is no longer any prophet,
and there is none among us who knows how long.
Asaph mourns for a nation that is without any light. Written in the situation of the destruction of the temple, probably during Babylon's invasion of Jerusalem, the viewpoint of this psalm is bleak. It is a lament. It is a song of weeping sung to the music of tears.
In verse nine Asaph laments not just the loss of the temple building itself, but the loss of any communication from the Lord. God has gone silent. And this was the hardest part of the situation to understand. The nation did not see God at work (there were no signs), did not hear from God (no prophet), and had no knowledge from God to understand their present pain (no one knows how long). It was an awful place to be... aware of sin and judgment and feeling so distant from God.
Yet, I notice that even as God seemed to give only silence toward them, they were not silent in respect to God. The judgment of God brought them back, in pain and with unanswered heartache, but back nonetheless in prayer to the Lord. And that may be the best strategy for dealing with the silence of God. If God seems far away (though really He is not) go after Him in prayer and pursuit of Him. Seek the Lord. Cry out to Him. Let Him know you are longing to see His hand at work, hear His voice in His Word, and know His will in the circumstances of your life. You will worship, and will find He answers such prayer!