When trying to get your security deposit, some landlords refuse to return all or parts of security deposits unfairly, knowing that it is difficult for a tenant who has moved away to return and sue. So when you move out, clean the premises properly and then ask the landlord to tour the premises with you so you can work out any disputes then and there.
After you’ve left, you might not be able to get back in to verify your claim (especially if another tenant has taken possession). If all else fails, don’t be afraid to sue. If the landlord refuses to return a security deposit that you have coming, sue him for breach of contract.
Some states (such as California) even allow you to recover extra “punitive” damages if he withheld the deposit “in bad faith.” You may bring your own suit in small claims court, or ask a tenant lawyer to represent you.