Short answer
– Psalm 119 does not give an author in its superscription. From a broadly evangelical standpoint the most likely traditional author is David (on grounds of tradition and thematic affinity), but many evangelicals also acknowledge the author is uncertain and some suggest a post‑exilic teacher who loved the Torah. Either way evangelicals hold the psalm as inspired Scripture and read it devotionally and doctrinally whether or not the human author is known.

Why David is often suggested
– Church tradition: David is the best‑known psalmist in the Bible and an early Christian and Jewish tradition often ascribes many anonymous psalms to him.
– Thematic affinity: Psalm 119’s mingling of suffering, prayer, trust, and deep delight in God’s law fits the portrait of “a man after God’s own heart” (Acts 13:22) and other Davidic laments and prayers.
– Liturgical and devotional use: Because of its penitential and personal tone many pre‑modern and evangelical preachers have read it as the work of an individual like David.

Why some evangelicals and scholars hesitate
– No superscription: Unlike many psalms, Psalm 119 has no heading identifying the author.
– Post‑exilic flavor: The intense, sustained focus on Torah vocabulary (law, statutes, commandments, precepts) and the polished alphabetical acrostic form have led some scholars to suggest a post‑exilic date or a priestly/teaching author who lived in a Torah‑centered community.
– Linguistic/style considerations: Some features of the Hebrew and the poem’s structure have made a precise dating or attribution difficult.

How most evangelicals handle the uncertainty
– Affirm inspiration: Even if the human author is unknown, evangelicals maintain Psalm 119 is God‑breathed (2 Timothy 3:16) and authoritative.
– Focus on theology and application: The psalm’s teaching about the trustworthiness, usefulness, and delight of God’s word is emphasized regardless of who penned it.
– Cautious humility: Many conservative commentators note the traditional attribution to David but admit the evidence is inconclusive.

A brief note on Psalm 119:143 (example translations)
– KJV: “Trouble and anguish have taken hold on me: yet thy commandments are my delights.”
– NIV: “Trouble and distress have come upon me, but your commands are my delight.”
Evangelical application: the verse models faithful response in suffering — honest lament combined with continuing delight in God’s revealed will. It encourages believers to treasure Scripture as a sustaining joy even amid trials.

Suggested evangelical resources for further study
– The Bible Knowledge Commentary (Old Testament notes)
– Derek Kidner, Psalms commentary (IVP)
– John Calvin’s commentary (also read devotionally)
– Shorter studies and sermons by evangelical pastors (e.g., Spurgeon’s sermons on Psalm 119)

If you’d like, I can summarize what several specific evangelical commentaries say about authorship and date, or give a short devotional reflection on verse 119:143. Which would you prefer?