This is not permissible. Praying to the qibla is a condition of prayer. You must try your level best either by looking at the position of the sun to find out the directions or to check a compass or your mobile or ask the locals or check the masjid.

Today i came to a place where i disnot know which side was qibla and i wanted to pray. So instead of missing the prayer in doubt of qibla direction i just spread the prayer mat n prayed. Will my prayer be accepted or should i go home and pray again?