Do not mail a second return. The IRS is currently not processing any mailed returns so it would just be put in a pile unopened and then slow things does down when the IRS starts processing mailed returns again because they now have to look at both of your returns and figure out why they have two of them. The IRS is also not taking any phone calls. There is nothing you can do right now but wait.
When the IRS does start processing mailed returns, you can track the status of your refund using the IRS tracking web site:
