Most landlords will ask you to pay a deposit and they have a good reason for asking for this. A deposit is like insurance against something going wrong in the property. However, it's important to remember that this money is your money and the landlord should only keep it if you have caused damage in the property, you owe rent to the landlord or you have failed to keep to the tenancy agreement and this means that the landlord has lost money.
You'll need to negotiate with your landlord to try to get your money back. Any negotiating should be done in writing and you need to keep copies of any emails or letters you send. If you're not able to agree with your landlord, you can go to Small Claims Court to see if a judge thinks you should get your money back.
Your landlord needs to have proper reasons to make a claim on your deposit money. All landlords have a legal responsibility to provide tenants with an inventory at the start of their tenancy. A good landlord should take a detailed inventory when you move into the property and use the same inventory when you move out of the property to check if the condition or cleanliness of the property has got a lot worse.
You can use the Small Claims Court to take legal action against someone if you are claiming less than £3000. You don't need a solicitor to go to Small Claims Court so the costs are much lower than the costs for other types of legal action.