Gayathri

सर्व चैतन्य रूपां तां आद्याम् शक्तिं च धीमहि बुद्धिं या नः प्रचोदयात्
sarva chaitanya roopaam taam aadyaam shaktim cha dheemahi buddhim yaa nah prachodayaat

Irrespective of caste,creed any body can recite the above mantra as a substitute for Gayathri Mantra.This will grant the desired result like gayathri

ॐ शिवाय गुरवे नमः
om sivaaya gurave namah

For those who are in need of Guru or who couldn't find a guru due to any reason can chant above mantra and make Shri Shiva(Parameshwara) as their guru.

by Sri Samavedam Shanmukha Sarma Garu