Diagnosing the problem.
ESTABLISH WHICH PROBLEM IT IS
Is anyone visiting? If not, it is a visibility problem. Are they visiting and not buying? A conversion problem. Are they buying and you are not profiting? A pricing or cost problem.
Three entirely different responses.
IF NOBODY IS VISITING
Is the site indexed? Does it rank for anything? Are you telling anyone it exists?
A new site produces little from search for months. Early customers come from people who already know you.
IF THEY VISIT AND DO NOT BUY
Is there a phone number? Does the form work? Is pricing available? Is it slow? Does it load properly on a phone?
Check the form first. A broken contact form accounts for a surprising share of "the site produces nothing".
IF YOU SELL AND DO NOT PROFIT
Calculate the real margin: goods, delivery including failures, gateway fees, packaging, your time.
Frequently one popular product is unprofitable and subsidised by the rest.
THE UNCOMFORTABLE POSSIBILITY
That the product or price is wrong. That is more common than a technical problem and harder to accept.