Start with the three approved schemes
If your landlord took a tenancy deposit for an assured shorthold tenancy, they normally had 30 days to protect it in an approved scheme. Search DPS, mydeposits and the Tenancy Deposit Scheme using the same details each time.
If none of the schemes can find a matching record, keep dated screenshots or confirmation emails. That evidence helps show what you checked and when.
Use the eligibility check as the next step before trying to work out the claim alone.
Compare scheme records with payment records
The payment date matters because the 30-day period normally runs from when the landlord or agent received the deposit. Bank statements, receipts and email confirmations can all help establish that date.
A missing scheme record does not automatically prove every legal point, but it is a strong reason to review the tenancy paperwork and prescribed information.
What the court can consider
If the rules were breached, the county court can order the landlord to deal with the deposit and may order compensation. The award can be up to three times the deposit, depending on the facts.