You have me confused! Your title says “stimulus payment.” Is that what’s missing?
Did you receive a separate letter saying that your stimulus was paid? It’s called form #1444.
If you received this letter (Notice 1444) in the mail and didn’t get your payment, you can check the Get My Payment tool on the IRS website to double-check that it has been issued. You can initiate a trace on your payment by calling the IRS at 800-919-9835 (expect long wait times) or submitting Form 3911.
That’s your best opportunity to find out where your stimulus check went. If it was sent back by the post office, then you’ll likely only be able to claim that amount when you file your 2020 return next April.
Now you also mentioned that your accountant looked for your “refund”. Is that what’s missing? If so, it’s the accountant’s responsibility to contact the IRS on your behalf.