Re Leasehold Query

Other

Hello,Going through my late parents effects as executor I have discovered that they owned the freehold of two maisonettes one of which I grew up in.
It would appear on further investigation that they did not insure the building as they should have done under the lease agreement or collect the ground rent.
I have also discovered having written to the land registry that the leases only have 69 years left to run.
Could you please advise:-
If the freehold would have any value and how are they valued
How I would go about selling it if financially feasible
What recourse the leaseholders would have if I contacted them after all these years would I then have to start insuring the property etc.
Many thanks & regards,