Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first
Which part of the Uk are you in
When did your parents pass away?
Just to check - the property is in both of their names?
You will need to obtain Letters of Administration for your fathers estate.
You do not need to obtain them for your mother's estate and the house passed to your father on her death automatically and therefore falls within his Estate
You can read about obtaining Letters of Administration here
Once you have these then you can complete an AS1 transferring the property into your name
Then you register it at the Land Registry using an AP1
Please ask if you need further detaols