Is there any way to reverse whatever happened?
I think it happened when I tried to add a signature to a part of the form.
It depends on what exactly happened. If the digital signature field was set to lock the fields you should be able to clear your signature and then re-enabled them. If it flattened them then there's no way back.
Signing is also designed to be absolutely final. So no need of form filling after that. You may have to start again.