Your IRA contributions are typically tax deductible. You should review your tax returns to establish when you made IRA contributions. If you itemized, look for a bank receipt or account number that identifies the institution holding your account. In the absence of account specifics, details relating to the amount and the timing of the deposit will help you narrow your search. This may not be the most accurate search since the value of the IRA may have risen or fallen since you established the account.
If your IRA cash began life in a 401(k) or similar plan and was rolled over, you should contact the human resources department of your former employer. The retirement plan custodians can tell you how the funds were disbursed. If the rollover was a direct transfer, the funds were sent directly to another bank or institution and deposited in an IRA. The plan custodian can give you the details. If you did an indirect rollover, the proceeds were sent to you as a check. You will need to search your records to find it.
All 50 states enforce escheatment laws, which require banks to surrender abandoned account proceeds to the state. In California, for one example, accounts are technically abandoned if there has been no contact with the owner for at least three years. If your lost IRA was established several years ago, then there's a good chance the money has long since been escheated to the state. Contact your state's unclaimed or abandoned property department to check. Many states have online databases that enable you to search for lost money by name or social security number.
You can always visit the bank that held your IRA. If it's no longer operating, contact the Federal Deposit Insurance Corporation. When a bank fails, the FDIC sells its assets -- including IRA deposit accounts -- to other institutions. The FDIC maintains an online list of failed banks and has a database through which you can search for contact information for such institutions. You can use this tool to contact the parties involved in the liquidation of the bank.