You can no longer e-file a 2016 tax return. It has to be printed, signed and mailed. If you are getting a refund, it will be OK to file past the deadline; you will not be penalized. However, if you owe tax due, get your return filed ASAP, as penalties have begun to accrue.
Do you mean you used a tax prep service at a brick and mortar H & R Block that neglected to submit your tax return, or did you use their software?