The most potent Durga Prayer for Navaratri "BHAVANYASHTAKAM (Eight stanzas of Bhavani Prayer)" written by Adi Shankara in Sanskrit translated in English:
3rd stanza
न जानामि दानं न च ध्यान-योगं, न जानामि तन्त्रं न च स्तोत्र-मन्त्रम्।
न जानामि पूजां न च न्यासयोगम्, गतिस्त्वं गतिस्त्वं त्वमेका भवानि।।
meaning
O Mother of the universe - I do not know how to come close to you.
I do not know any form of puja, or prayers, or how to worship you at all.
Help me, O Mother Divine - You are my only saviour, my eternal refuge.