USPS loses my state tax forms in the mail and tracking stopped, and with their failed delivery, does this mean I'll have to re-file late? I didn't owe payments.

The postmark date was before 4/15, so I was on time. But now it looks like either my mail is missing or they just stopped tracking. Do I re-file? But then does this mean I filed late? I don't owe tax payments, just a refund from state. I didn't think USPS would mess up again, so I also wasn't able to file an extension..

Thank you.