Landlord will not return the deposit and stopped replying

What we told them

Check first whether the deposit was ever protected in a statutory scheme — in most jurisdictions that is a legal requirement with penalties attached, and the scheme runs free adjudication you can use without a lawyer. Look up the deposit by your tenancy details rather than asking the landlord. If it was never protected, the silence has just cost them considerably more than the deposit, and that fact usually restarts the conversation.