If a landlord terminates a rental agreement for unproven reasons, would a person be entitled to their security deposit returned?

Is this a rent or a lease ?

And it may end up going to court to determine if they should pay or not.

What were the reasons given?

Was there other damage to the property that the deposit would be used for?
Was there unpaid rent ?

Lots of questions and you give us little to work with. Answer Chuck's questions please. We can't even tell if this is a rental home , apartment or maybe even a business.

The security deposit is designed to protect the landlord against loss due to damage or unpaid rent.

So, if there were damages or unpaid rent, they can keep your deposit. However, they are required to give you notice about how the deposit is used within a specific space of time.

More details including location (ANY question on law needs to include your general locale as laws vary by area.) would help us help you.