A few things to try:
1. Call the title company and ask where your earnest money deposit is and ask for it to be returned if they are holding it.
2. Call the REALTORS brokerage office and demand to speak with the head broker about where your earnest money check is and that it be returned.
3. If number 2 does not answer to your satisfaction then tell them you will be calling their state real estate commission about what happened with your earnest money.
If the REALTOR is holding your check or misplaced it they are not supposed to do that and it should be a real estate commission violation. Your purchase offer should explain who is holding the earnest money and under what conditions it will be returned to you and what type of account it is held in and whether that is interest bearing or not and who retains the interest on the money.
With future offers it would be better to put under the earnest money section (upon written acceptance) in the purchase and sale offer. This means unless the offer is accepted in writing you do not give the earnest money to be held. This way you do not have to give an earnest money check every time you submit an offer but only if you go under contract.
Hope it helps.