Answer

If Sthapna Ji is not available, you should not perform the ritual casually or replace it with something improper.

You may do the following respectfully:

• Do Namaskar Mahamantra with devotion.
• Do bhav-puja mentally, with pure feelings.
• Pray with humility and say that due to absence of Sthapna Ji, you are offering devotion through inner bhav.
• If possible, ask a knowledgeable Jain elder, pujari, or guru-bhagwant for guidance according to your tradition.

Explanation

In Jain Dharma, external objects used in puja or ritual should be handled with proper maryada. If the proper Sthapna Ji is not available, the most important thing is to maintain shraddha, vinay, and shuddh bhav.

Do not invent a substitute unless your family or sampraday tradition specifically allows it.

Takeaway

When Sthapna Ji is not available, do devotion through Namaskar Mahamantra and bhav-puja, and follow proper guidance before doing the full ritual.