You could potentially, go to Turbotax online under a different account name and password, and create a new tax return, being careful to enter the 1099-R correctly. It might turn out that you owe more tax, if you somehow didn't enter the income but did enter the withholding. I would still not attempt to file a new return or an amended return. Just send the 1099-R copy as requested. But, if you find that you made a mistake previously, you won't be surprised when the IRS sends a bill, and you can start preparing your funds if you need time to do so.
Or, maybe you don't owe tax and you are misreading your original return. But either way, if the IRS is only asking for the 1099-R, I would just send that and wait for their next response.
