If you mailed the return, unless you used a method that has tracking such as Priority Mail or certified return receipt, you won't know for some time if they received it.
Since you are due a Federal refund, at approximately 4 weeks after mailing, you see it show up in this IRS tool "Where's My Refund":
https://www.irs.gov/refunds
It takes about 6 weeks from mailing to get a Federal refund for a paper return.
