Does the council own this fence?
If so, then provided it’s not dangerous, I’m sorry to tell you that you cannot compel them to put the fence back up. There may be a provision in the leasehold property for the fence to be maintained but if the property is not leasehold and there is no covenant by the council to maintain the fence (it would be very unusual) then the council are free to let the fence fall down provided it does not injure anybody or trespass on your property or remove it completely.
Notwithstanding the above, the legal costs of taking action against the council to put a new gate and fence in would be far more and riskier than simply putting up the fence yourself.
By all means make a complaint to the council and if that falls on deaf ears, make a complaint to the Local Government Ombudsman for the legal situation is that the council cannot be compelled to do this. They may respond to a complaint however to the Ombudsman.
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