I am losing many orders by my reply... What's wrong with my reply message?

Two things.

1. Grammar
2. Marketing

The grammar issue needs to be addressed. You can visit amazon.com and find plenty of books that can help you with that issue.

Next, your most valuable skill you'll need to learn is how to market yourself.

Learn how to use your marketing in such a way that you attract the right kind of clients. The easy way to do this is by simply setting up a funnel system for your services that gets suspects to raise their hands.

Then you turn those suspects into prospects.

Then you turn those prospects into clients.

Then you turn those clients into premium clients.

Then you turn those premium clients into champions for your services.