I am afraid that, if he is unwilling to return your deposit voluntarily, and if you have not used an escrow service, then the only way to recover your deposit is through the Courts. However, without any proof of how you left the property, your chances at being successful are reduced and the costs of the whole procedure might outweigh the benefits of such an action.

Its never a bad idea to instruct a lawyer at the time of returning the property back to your landlord. He would have drafted a document stating the landlord's conformity with the property and obtained evidence to prove your compliance (which would have been favourable should you need to reclaim this at Court).

I understand the current situation must be very frustrating and wish you the best in recovering these monies owed to you,